The rap in Philadelphia on Erdy McHenry Architects is that their buildings are show-offs. They're too stylish, too trendy. They lack real depth. You don't want to look too closely at the details, either.

Even worse, if you follow the local architectural chatter, the firm has eagerly fed Drexel University's appetite for buildings that brand. Having produced two very distinctive dormitory designs in just three years, Erdy McHenry has been accused of aiding and abetting Drexel in its mad plan to create an architectural zoo on its West Philadelphia campus.

There is some truth to the criticism, especially as far as the roughness of the detailing goes, although I would argue that the buildings' rough treatment of their neighbors is a bigger concern.

It is also true that the firm's buildings tend to grab you by the lapels. But demanding to be looked at is not a fatal flaw in itself, and, given Philadelphia's congenital preference for extreme architectural reticence, it may be a positive trait. In any case, the complaint strikes me as a narrow reading of their work, which is among the most interesting in Philadelphia today.

Their new dorm, Millennium Hall, is sure to fire up the debates. Not only is it Drexel's tallest building yet, the 17-story tower on 34th Street has the elliptical profile of a football, and it rides the skyline like an oversized Leaning Tower of Pisa. It is, at once, their most ambitious and most flawed design.

Most of Erdy McHenry's previous Philadelphia projects have been big, horizontal slabs - the Edge at Temple University, the Radian at Penn, the Piazza at Schmidts in Northern Liberties. The architects liken the form to skyscrapers on their sides. Because the tiny Drexel site, a former tennis court just south of Powelton Avenue, precluded a slab, it forced the architects to go vertical. It's nice to see the firm move away from the wide slab, which can get pretty oppressive.

For a first tower, Millennium Hall was conceived with no shortage of brio. It's not just the unusual shape, or the silvery sheen of the aluminum panels that hug its curves like the latest bondage dress.

Typically with tall buildings, the placement of each floor mirrors the one below. But here, each successive, 5,000-square-foot plate shifts 10 inches off center, so that by the time you get to the top, the ovoid floors have rotated by 13 feet. The 202-foot tower, which cost more than $40 million, almost seems to spin.

That staggered arrangement is what gives Millennium Hall its leaning aspect. The angle can easily be glimpsed in the deep, glass-lined clefts that split open the ellipses on the east and west sides. The unusual geometry means that the tower looks different from every vantage, much like its West Philly neighbor, the Cira Centre. The appealing shape-shifting is fascinating from both near and far.

Figuring out how to engineer this rotation was so complicated that Erdy McHenry had to enlist both Arup's Cecil Balmond, the man who made Rem Koolhaas' oppressively cantilevered CCTV tower in Beijing stand up, and the local structural experts at the Harman Group. If you look carefully through the glass clefts, you can see the exposed concrete columns angling up through the building.

Those concrete columns act like stilts to lift the building off the ground, in the manner of Le Corbusier's pilotis. They're the key to understanding what makes Erdy McHenry more than just a deft bunch of stylists.

In their best work, such as the Hancock Square building at Schmidts, the design is the structure, and the structure is the design. Everything else is just a screen to keep the weather out. That's a very different strategy than you would see in a Frank Gehry building, where a steel frame is used to support a sculptural, and some might say, arbitrary volume.

Erdy McHenry's emphasis on structure is what gives Millennium Hall its basic integrity. The architects didn't rotate the building just for fun. By turning each floor slightly, they were able to arrange the exterior's aluminum screens to deflect the sun where it hits the building with its greatest ferocity. At the same time, they placed heat-deflecting windows so the majority of the 482 occupants will have spectacular views of Center City's skyline.

That's very nice for the people on the inside, but there are serious problems with the building at the ground level - more serious than any of Erdy McHenry's previous projects. While the architects argue that a slender tower is less intrusive than a bulky structure that filled the site, they never found a way to mediate the high-rise's abrupt change in scale from the largely Victorian neighborhood.

One rationale for elevating the tower on pilotis was to soften its landing and open a path into Drexel's evolving greenway. But the concessions are undermined by the tower's one-story companion, which houses an apartment for the dorm's adviser and mechanical systems. All three sides are blank walls, including the one facing the greenway. The south-facing wall is worse: With its corrugated metal and a visible cooling tower, it looks like the back end of a refrigerated warehouse.

The price of designing this exciting form does seem to be a weakness in the details. You can actually see the fire stairs' unattractive green insulation boards pressing against the glass in the two clefts. What's the point of spectacular windows if they're blocked? The views from top-floor event space may be breathtaking - but seen from a distance, the penthouse takes on the appearance of a classical colonnade. Weird.

For all its timidity, Philadelphia architecture has a legacy of superb craftsmanship and strong urbanism. Surely, there must be a place where imagination and style can meet craft and context.

Contact architecture critic Inga Saffron at 215-854-2213 or