I like this game but it does have a lot of glitches and bugs which are sort of becoming an Obsidian trademark in the gamer community (just warning you, Obsidian).
My list:
FISTO keeps giving me caps every time I tell him I don't want his services (which ends the conversation). He does this after he gets to the Atomic Wrangler. I could probably get unlimited caps from this.
There's an NCR station on the strip (LVB Station? LBM - something like that) and if you go upstairs there's a place where some guards will say "if you come any closer we'll attack" or somesuch. The problem is that half the time you don't get the warning before you're already over "the line" and then you end up with 5 or 6 NCR wailing on you. Why couldn't the door just have a pickable lock on it that activates the guards after you pick it? It's better than randomly getting attacked for walking in to the "wrong area" with a warning that only works half the time. The first time I did it I didn't hear any warning at all.
After I get the beret from the guy in the dinosaur's mouth, I can ask the dude who runs the dinosaur shop to go stand in front of the dinosaur (to get killed presumably). Nobody else in the Novac hotel gives me this option. Is he the one? Later the option went away. What happened? I didn't finish that quest so I don't know who I was supposed to tell to stand in front of the dinosaur. I just thought it was weird that he had this option.
After I got done talking to Mr. House (outside after I left his casino) this girl from The Followers runs up to me and says "Did you bug Mr. House like we talked about?" The thing here is that I didn't know what she was talking about because I'd never seen her before.
The girl in the Vault 21 hotel (the shopkeeper) has a different voice when she says goodbye than she does when she talks in conversation. I want to say her voice for hello is different too.
The interface for the Caravan card game is bad in general and it's confusing to play on top of that. There was a tutorial level for the game, why isn't there a tutorial for Caravan? Why doesn't it tell me on screen that I can use the arrow keys to navigate the cards? It gives me a mouse cursor, which makes me think I should be able to use the mouse to click and drag cards.
When I tell Steam to "verify the integrity of game cache" it always tells me that it has one file to replace but it never does it.
When I click on the mainframe that is supposed to let me upgrade my presidential suite (or whatever your "room" is called) at Mr. House's place, it changes into a vendor interface, but it won't allow me to click any of the upgrades. The menu gets really glitchy and all I can do is close it or try to sell things to it, which makes no sense. No upgrades for me I guess..

I got the King's dog Rex to take it to get fixed. I had a conversation with it and told it to "only attack enemies I attack". As I am wandering around it runs off to attack cavadors! Of course it dies. I talked to it many more times trying to reset it to "only attack enemies I attack" but it would always run off to attack the stupid cavadors. I finally gave up on him and parked him in a store somewhere.
Where are all the prosttutes in the Atomic Wrangler? The bartender says that they are supposed to be there, but I never see anyone inside except her brother, some gamblers at the table, and an insult comic. I can recruit some prosttutes to work there, but that's a quest. Why would the bartender go on a shpiel about how their prosttutes aren't slaves unless they already had some on staff? Why do I never see any customers at the Atomic wrangler either? They are supposed to be popular on Freeside.
The game is super-slow whenever there are human NPCs on screen.
There is a copy of the Wasteland Survival Guide in a campground between Goodsprings and that NCR outpost with the statues. If you don't click it just right or try to move it the book will fall underneath the ground and you won't be able to get it anymore.
Whenever I go back to Goodsprings the Powder Ganger bodies are still sitting there in the middle of town. Doesn't anyone take them away? Can't they rot or something? I found out that they do eventually go away.
The Powder Gangers were shooting me on site until I got to their base. When I got there I was able to pay some guy to get inside and none of the people in their shot at me even though they were supposedly in the same faction. I can't tell if they like me or not - the reputation system is unclear.