More of the same is good.
What I love about Fallout is the genuine sensation of exploring a massive, exciting world that I experience while playing it. Every time I am notified that I have discovered a new location I get a small rush from knowing that my world map is a little closer to completion. Finding a unique or particularly valuable item does the same. This game is filled with small scale victories that will keep you playing all day long.
As for the story which I notice is often berated as a low point of the game all I can really say is that while it isn't great it's not bad either, but if you are playing this game for story or character development you are playing it for all the wrong reasons.
Things that improved upon from Fallout 3 include deeper crafting, as you are able to create and breakdown ammo as well as make specific aid items at campfires rather than receive a random item from your chemistry set. These are really nice additions as you won't be stuck with a thousand rounds of ammo for a weapon type that you never use, I am sure the campfire has a lot of potential as well, but I haven't really built up my survival skill so it is not something I use often.
Your travelling companions have been improved upon as well, the ability to travel with two rather than one gives you several potential configurations that will for better or worse make combat a breeze. They also open up quests if you talk with them after certain criteria have been met, adding more content to an already loaded game.
Then there is the reputation system, which causes a group or town to react to you in accord with your actions, this is nice because I thought it was silly how in FO3 I could go into Rivet City kill several gaurds so I could use there SMGs for repairs and return a day later with no consequences. Under this system the NPCs are not so suicidally forgiving and the game is better for it. There are still problems with NPC behavior though, mainly the hostility toward thievery, as in the last game if you are observed even accidentally picking up an item that is not yours will result in the NPC who resides on the property to become so hostile that they will fight to the death, regardless of rep or having done some great favor for them. I just feel like you should have the opportunity to apologise.
A note about the GS review's claim that the game is "absolutely swarming" with "disastrous bugs," whoever wrote that is a bit of a drama queen. While it is definitely flawed here and there it is not as deeply flawed as those over the top statments would indicate.
Well over fifty hours into the game I have had a handful of freezes which are admittedly crap because you have to power down the console and start it back up and potentially lose a good deal of progress, but given the frequency of autosave this is not often the case, and the worst is generally just having to wait a few minutes to restart the console and load the game again.
Apart from that there are minor flaws that we already saw in Fallout 3, floating items, enemies stuck in walls or rocks, the occasional unlootable corpse. These things do not occur frequently however and are actually kind of amusing when they do.
I really doubt that forum posters who say things like "bugs ruined the game" have actually played much of this game if they have played it at all. Yes it does have buggy patches and incidents but if you think it ruins this fantastic game you are just believing reviews rather than seeing for yourself.
Overall I give this game a 9 out of 10 and recommend it for anyone who enjoys western RPGs. Strap on your Pip Boy and get out there!