In the Cira Centre lobby, it evolves by the hour, by the day, in its look and its palette of New American flavors.

Bland opinions are scarce when it comes to the Cira Centre, the prismatic glass tower designed by Cesar Pelli that rises next to 30th Street Station like a skyscraper made of quartz.

My feelings change drastically depending upon the hour. I marvel by day at the artistry of its shimmering, jaunty shape, how blue skies and clouds get turned askew in the mirrored reflection of its slicing walls. At night, though, when the artless glitz of patterned lights blink and scroll cheesily across its face, I just hope it won't cause an accident on the Schuylkill Expressway.

It seems only fitting, then, that Rae, Daniel Stern's new restaurant inside the Cira Centre's lobby, should be a chameleon, too. In look, concept, and even in its broad palette of New American flavors, Rae's identity depends on when and why you come.

Is it a stylish new lunch room and happy-hour hangout for the corporate suits in the offices upstairs, who can step from the elevator into plates of chopped salad and smoked-rabbit nachos? A cutting-edge train-station bar for nibbling on venison cheesesteak with a glass of old-vine syrah before Metrolining off to D.C.? A banquet powerhouse with private rooms that can seat from six to 350? Or a sparkling culinary destination for diners who have eagerly followed Stern's trajectory from Le Bec-Fin to Gayle, the cozy gastro-boutique he still operates in Queen Village?

Rae aspires to all of those things with admirable ambition. And along with polished service and an impressive 200-label cellar, it serves up more than a few glimpses of Stern's culinary prowess. But it has yet to achieve the complete consistency I'd hoped for from one of the year's biggest openings.

The curving bar and lounge, which takes a sweeping dip into the stark-white lobby, is the restaurant's most successful venue. It shares the building's need for daylight, and sunshine illuminates the space with a warmth that is a natural balance to the crisp contemporary design. Center City's skyline hovers splendidly through the lobby's front windows like an inspired urban tableau.

But that view unexpectedly disappears at night, when interior lights cast a glare on the lobby windows. And just as the destination diners arrive for dinner, Rae suddenly begins to feel like a rambling restaurant stuck behind the escalator to 30th Street Station.

It's not an unpleasant space, with its sleek white-leather chairs, cool modern colors, white scrim curtains, and a see-through wine cellar on the mezzanine above the room. But after sunset, Rae no longer draws energy from its unique vantage points.

That vibrance must come from the glassed-in, open kitchen that hums at the center of the room. And though some creations worked better than others - perhaps a symptom of Rae's overly complicated menu format - Stern delivered a number of memorable flavors that showcase his trademark gastronomic juggling.

The veal "kreplach" are an homage to his grandmother, Rae Radow, who inspired the restaurant's name. But even Stern's Bubby probably didn't make them quite this good, stuffing the saffron ravioli with garlicky, herbed veal breast, then topping them off with veal jus and roasted artichokes.

Was that a cone of liver gelato on the foie gras tasting? Blended with prunes and Armagnac into a sublimely silky mousse, it's worth a double scoop.

Stern also has a penchant for elevating bar food to haute new guises, and he indulges that to the hilt, from the smoked-rabbit nachos (really empanadas) to the venison steak sandwich topped with truffled cheese. Crisp potato skins come piled into platters laden with smoked salmon tartare. Greaseless, deep-fried "fingers" of risotto croquettes exude the heady perfume of truffle. And micro-thin pizzas emerge from Rae's brick oven beneath an array of upscale toppings, my favorite being a wasabi-cilantro puree draped with cool pink tuna carpaccio and citrus-dusted popcorn.

Stern even has a great twist on the marshmallow, infusing celery root into a sweet and savory meringue cube that melts atop the "snapper, snapper soup." Perched over a beautiful slice of red snapper, saffron-scented fish dumplings, and a lemony beer fumet sauce, the dish had vibrant flavors and an ethereal lightness that many of the other dishes lacked.

To begin with, the portions are enormous, which may be a good thing considering the lofty prices ($24 to $52). But it didn't always serve the compositions well - especially meat entrees that came drowned in dark pools of intensely reduced gravy. This was even true of items that came from the menu's "standards" list, which supposedly offered simpler dishes than those from the menu's creative "renditions" side.

The Middle Eastern-spiced rack of lamb was one notable exception, the tender meat sparkling beneath a crust of spicy harissa and chickpeas. But both the tenderloin topped with marrow ravioli and the rabbit medley (with a side crock of dense cassoulet) needed a lighter touch.

There was so much produce piled atop the otherwise tasty Rae burger (carrots? jicama?) that it was a challenge just to hold. There was too much cheese on the mini-Reubens, whose smoky, house-cured pastrami lacked peppery punch. Too much mustard cream cheese weighed down the excellent house-cured salmon. The tender, oil-poached salmon was overwhelmed with horseradish tang.

An elegant balance was restored in pastry chef Elizabeth Brozoski's smart desserts, from the fluffy white-chocolate mousse topped with toasted hazelnuts, to the superb house-churned ice creams, a comforting apple-walnut pie, and a very memorable cheesecake. It was crowned with strawberries and - crunchy, sweet, surprising candied celery.

Hey, if Rae can turn celery into a convincing sweet finale, there's no limit to what this restaurant can become with a little more polish. I may even learn to really appreciate the Cira Centre when the sun goes down.

Contact restaurant critic Craig LaBan at 215-854-2682 or claban@phillynews.com.

Read his recent work at http://go.philly.com/craiglaban.