I'm very happy to have the Loew's as my neighborhood theater. It's huge, clean, and has every major movie out, including 3D and iMax screens. Great sound systems and sharp pictures with comfortable stadium seats that provide good views from every angle.
It also has a bar/restaurant for parties before the show (We all dressed in tuxes and evening gowns, and ordered Martini's before seeing the last James Bond Movie) and some arcade games and air hockey if you've got time to kill before your show.
The only gripes I have is it can be pricey, currently up to $13 for an imax 3D ticket and glasses. Lines can be slow for concessions and popcorn and soda can tack another $10+ on top. So to stretch your dollar I'd recommend stopping for food before or after at one of the dozens of locations the Waterfront offers, and hitting a 1/2 price Matinee if you can. At any price, I think the Loews is one of the best places to watch a movie in Pittsburgh!