Opinion: SANAA's new river-inspired building in New Canaan may be beautiful, says Alexandra Lange, but it is still unclear whether its community-focussed programme will be useful to anyone.

Grace Farms is beautiful. The centrepiece of the site is the sinuous 83,000-square-foot, $67 million building called The River, designed by SANAA and set on 80 acres of open space in tony, architecturally-exceptional New Canaan, Connecticut. The River flows downhill, 1,400 feet long, covering a 44-foot elevation change.

The aluminium roof, which glows in daylight like iridescent ceramic tile, covers indoor spaces on four levels: the sanctuary up top, the library one level below, the commons beyond, bottoming out in a bi-level sunken gymnasium, surely among the most spectacular places to play a pick-up game in the country, if not the world.

Grace Farms is curvaceous. The walls enclosing each of these ceremonial spaces are curved, double-glazed glass lights, 203 of them, into which SANAA has inserted curved and bubblicious light fixtures, curved benches, circular chairs (squishy and hard), circular BBQ pits, clover-leaf tables and clover-leaf ottomans, kid chairs with curvy bunny ears. Even the pits of loose gravel, intended to catch the rain off the gutters, have a precise, metal-edged curve. Many of these fixtures are custom and contract SANAA, underlining how pervasive these forms – like that of the thin roof on thinner supports – are in their work.

SANAA's previous American building built of bubbles, the Glass Pavilion at the Toledo Museum of Art, grouped those enclosures under a rectangular roof. The River snips them apart, and becomes more interesting as it gets weird – in the stretchy bits between the pods of program, where the roof has to dive down a slope, thin to make it across an open plateau, or fold back on itself to cover one of the solid-walled ellipses holding the WCs. If the metallic top of the roof suggests the ceremonial surface of a Japanese temple, the underside is all unpretentious warmth, Douglas fir running from inside to out in an eave of shifting depth.

But what is Grace Farms? The first 48 acres of the site were purchased in 2007 by members of Grace Community Church, founded 2001 "to explore how the lessons of the Bible applied to modern day life". The programme morphed in the face of community opposition to a 1,200-person sanctuary on winding residential roads. Now the land and buildings are owned by the non-profit Grace Farms Foundation, which calls it "a new centre for nature, arts, community, justice and faith." What that means is decidedly unclear, cloaked in polite evasion and (on the Grace Farms website) liberal use of the passive voice.

On the day of the opening, president of the foundation Sharon Prince responded to direct questions about the project's endowment, fees for use, and future means of support by talking about Heavenly Roast, a coffee blend sourced from women-owned farms. There's also a gift shop. Since Prince and her husband Robert are founding members of the church, and he is co-chief investment officer of the hedge fund Bridgewater, it may not matter, but a private operating foundation means you don't have to reveal that information. Or pay taxes.

Despite the project's turn away from the specific program of a church, I found it difficult not to read Christian symbolism into the architecture. The 700-person sanctuary sits at the top of The River, almost 44 feet above the gymnasium, reached up a flight of steep steps arranged so that the Pilgrim's Progress of backlit bodies is visible from below. Grace Community Church will hold services there on Sunday mornings, and has administrative space in another building.

The stairs and their angular galvanised steel handrail are among few sharp elements in the ensemble, making them all the more visible. For the commons, an oval dining hall on a central plateau, SANAA created minimal circular chandeliers, suspended by slender strings from the Douglas fir ceiling: they look like three halos waiting for their angels.

The sanctuary could have been the latest entrant into the history of Modernist temple design, part of a tradition of hovering roofs that includes Eero Saarinen's North Christian Church in Columbus, Indiana, and Minoru Yamasaki's Temple Beth El in Bloomfield Township, Michigan. But while the 95-foot glulam beams that enable the column-free space are impressive, the overall effect is generic: a tasteful bowl (organic, fair trade, gluten-free) of creamy upholstered chairs and a ribbon of view.

Indeed, without their names and carefully arranged furniture, all of the glass bubbles' programs might be interchangeable. The library, after all, consists of just a handful of highly curated bookshelves, one for architecture, one for faith, one for justice, and so on. The commons is established by refectory tables milled from the wood of trees that had to be sacrificed to build the structure. The chairs that line the sanctuary are nicer than those in the gym, but there's no reason they couldn't be switched. The program, beyond the church purposes, seems notional.

"Select non-profit institutions and community organisations whose missions correspond to Grace Farms' will benefit from the gift of programme space in The River," says the press release, but there's no place on the website to apply – they call you. The world's top advisors are weighing in on art, justice and faith, but for the rest of us it is the "community" plank that matters.

The site is open to the public from nine to nine, five days a week, with food service and a reading room, along with outdoor trails. The gym is open weekday afternoons. Services are held in the sanctuary Sunday morning. Prince mentioned children stopping in after school to do their homework. Seeing a cord snaking out of one of the flush floor grills, I wondered if there were enough outlets should teenagers decide it was nicer than the New Canaan Public Library.

If Grace Farms' New Canaan neighbours like the Glass House and the Noyes House teach us anything, it is that modern interiors pointed at a view can be shaped and variable, including courtyards to showcase sculpture or Japanese-inspired near landscapes, or lighting to make the walls disappear. Such tuning distinguishes them from one another, knitting them closer to their sites – but never trying to disappear. They also teach us that landscape is a construct, groomed, shaped and planted. The lack of specificity in the design of and verbiage around SANAA's building, however, seeks to erase that hard-earned knowledge, presenting itself as a natural growth out of the existing terrain, less architecture than frozen spring.

Yet the stylised roof and bubble buildings are really just the tip of a ledge. At several points along The River, ramps and stairs cut deep into the ground underneath, indicating the levels required below to make it look effortless up top. This isn't a self-reliant, light-on-the-land wilderness retreat, but a trophy building with an all-star panel of advisors. It may be free and open to the public, but its location severely limits the community that is likely to find it accessible.

Away from the architectural photography, there are several regular old orthogonal buildings, and attendant parking lots, including a barn renovated by SANAA (who removed all trace of previous use). The barn will "house many of the day-to-day programs, with classrooms, an art studio, a rehearsal space with sprung floor, offices, a lounge, a nursery and a drop-off food pantry to support the justice program." Many activities, raising the question again: What's The River for?

Perhaps all of this is in good faith as well as good taste. Grace Farms is certainly a land-use improvement on the 10 McMansions might have been built on the 48 acres. The best way to discover The River's true depths, however, is for the local citizenry to use it. You didn't beat the traffic, join it! Tutor your students at the Library, drive your basketball league to the gym, meet your book group at the commons, haul your tackle to the pond, picnic on the lawns so new you can still see the sod's seams. JUST DON'T BRING YOUR DRONE. Next year, take your kids to the SANAA-designed playground. Test the limits of this proffered public-ness. Then we'll see what community a glass pavilion really can create.

Top image by Iwan Baan.

Alexandra Lange is a New York-based architecture and design critic. She was a Loeb Fellow at Harvard's Graduate School of Design for academic year 2013-2014 and is the author of Writing About Architecture: Mastering the Language of Buildings and Cities as well as the e-book The Dot-Com City: Silicon Valley Urbanism.