I've played this game about 18 hours, I haven't encountered many glitches at all. All I've seen so far is a couple of typo's when having a conversation with someone and a Radscorpion partly submerged into the ground. Maybe PC users have it lucky.. who knows.
You must be new to PC gaming.
In PC gaming, because we all have unique hardware/software combinations, games can actually have significantly different results; meaning you can experience anywhere from no glitches, to being the most glitch-ridden game you've ever seen.
This is why there are system requirements (but it's of little use, because the hardware the supports the game works in a non-standardized proprietary format, which can lead to bugs)
For an XB360 game, what's the system requirement? That you merely have the XB360. Because it is set hardware; the game can be expected from a hardware point to run similar to other units. This isn't the case on PC.
So unless you were gloating that you didn't get any glitches, that should better inform you why you are experiencing glitch-free play. Personally, I crash religiously every 30-90 minutes. And it has nothing to do with not meeting and exceeding system requirements.