If your gripes with Aliens: Colonial Marines revolve chiefly around its doors, you'll love the day-one patches! Gearbox has detailed exactly what was in those updates dropped on launch day: performance improvements; a lot of love for doors; and other assorted bug fixes. You'll want to go online and download the patch if you haven't already.
Door-oriented changes including fixing some doors not openly properly, certain doorways blocking shots even when the door's open, doors bugging out if an alien's killed while it's being opened, and the Raven sometimes glitching through welded doors.
There's more to it than doors, of course. The three platforms' patches are almost identical, with the console versions simply having fixes for their splitscreen mode too, but here: full patch notes for PC; Xbox 360; and PlayStation 3. On all platforms, the patch will download automatically when you launch the game while online. Maybe you have it already, maybe you don't.
Of course, bug fixes can only do so much for a game game agreed to have far deeper flaws.