A great game that became a technical nightmare.
If you've played Fallout 3 you'll have no issues adapting to this game, after all new Vegas does use the same engine as Fallout 3 did. Also the new features such as weapon mods and different ammo types are easy to get used to.
One of the major features I did like is the weapon modification system, and the different ammo types, it can make say a 9MM pistol quite effective early in the game if you use the right modifications and ammo type.
I also loved the faction reputation system, it forces you to think about you're actions. Doing quests for one group could lower your reputation with another group. It forces the player to think.
In some cases if you have a bad rep with a certain group they may send out assassins to kill you.
Also the game offers quests which can instantly boost your rep with a group should it be too low.
Even offering a kid irradiated bubble gum lowers your reputation.
Although the reputation system is great it does have it's drawbacks;
You see, there are two major factions; Ceaser's Legion (Pronounced Ka-sar), and the NCR, I found that it was much easier to help the NCR then it was the legion since you'll most likely encounter more NCR troops.
The quests are long and varied, and in some cases if you lack a particular skill, there is always another way to complete the quest, sometimes even passing a speech check means you can complete the quest without doing anything.
The addition of the "Hardcore" mode adds more survival aspects to the game, meaning; Ammo has weight, you need to keep hydrated, and you also need to sleep often. The only downside to this mode, is that all you get is an achievement, and its not a huge incentive to play in hardcore mode. It is there for those who want the challenging experience.
They have also added a new perk called "Wild Wasteland" which makes the game a bit more wacky, and more odd occurances such as; Finding Indiana Jones in a fridge, Old ladies trying to hit you with a rolling pin because you stole their ..... .... sex bot (No joke!), Aliens, Uncle Owen and Aunt Buru and many more. These are indicated by an eerie sound. Honestly you could spend hours searching for these odd things.
Although the game is great and has excellent replay value it is plagued by crashes, freezes, blurred textures, long loading times, audio glitches and scripting glitches make this one of the worst games from a technical standpoint.
If you manage to look past all these technical bugs, you'll have tons of fun playing this game.
(Update: They have managed to patch most of the crashes but there are still some places where the game crashes, check on the fallout wiki for more information on these.)