Some people will tell you it is. Others will not. I myself have not experienced a single major glitch in over ten hours of playing (unless you count the quicksave bug, but I always use manual saves anyway). I would hardly call it a "glitchy mess".
May depend on the platform, they are not equal in terms of bugs.
There is a Nasty save bug in the PC version, but so far I have had only 1 crash. My friend at work plays on the PS/3 and also has only 1 crash so far. I have heard the 360 version is a mess however. My other work friend has real issues with it.
Xbox360 is not bugged much. Only had 2-3 bugs since start playing (18h played atm). But once one strange thing happened, i came out of a door and was stuck between something invisible and after pointing down i saw ''Pick up [random item]'' there were thousands of invisible items on the floor. after getting unstucked i shot on the floor and 4-5 dogs randomly spawned and attacked me. Straange moment.