As I mentioned previously, I finally got FO3 mid December and I'm about 20 hours into my second game at the moment. I have refrained from looking at this post until now.
First of all, let's not kid ourselves... Bethesda nailed it. The look, atmosphere and harsh reality of post nuclear life... Absolutely nailed it. At first I was cursing the chronic lack of ammo, but once I changed my playing style a bit (baseball bats are better than the rifle for taking out radroaches) I found that it just adds to the believability of (and immersion in) the world.
I had no misgivings about Fallout flavoured Oblivion because I quite liked the latter. However, I will agree with others here that it really tastes nothing like Oblivion.
It is slightly more of an FPS than I would have liked (since you have to wait for VATS to recharge), but I forgave Deus Ex of the same sin because it was such a brilliant experience and so ditto for FO3. More than once I've found myself looking at the ceiling after having spun around three times because a feral ghoul has jumped out of the shadows and my mouse ended up halfway over the keyboard.
I hated the ending. I agree with others that it was ill-conceived, poorly implemented and the most significant disappointment in the game, and for similar reasons to those already mentioned.
My other significant gripe was with the "radar" and mapping system. Particularly when inside, I would have liked to have been able to tell from the red lines on the HUD whether the enemy was on my floor, above or below me. Or, for that matter, behind me. We have had a perfectly serviceable interface for this type of information since "Elite" came out in the 80s and I think that it's criminal that we don't use it (or something similar). As for the mapping system, I will refer you to the late 80s/early 90s game "Decent" which showed that usable 3d maps are possible. The local view maps in FO3 are beyond useless.
Yes, I know that they're similar to the ones in previous fallout games (which were equally rubbish), so there is an argument for consistency, but it's the Pipboy 3000, so they could have done it. In the absence of an actual operational mapping system, the inclusion of flares (to mark where I've been) certainly would have helped my subterranean navigation.
I also would have liked to be able to add permanent notes to the maps or notes in the Pipboy (a la "Planescape:Torment").
I did like the several nods to the old CRPG "Wasteland" in FO3. The Citadel, Vax, etc. (I saw a few toasters, but none of them were broken). Nothing to get the lawyers upset about, but nice.
I was unimpressed with the level cap (I just don't like them in any RPG), although I can see that it makes levelling opponents much less noticeable. Also, I hit lvl 20 not too far before the end so at least they seem to have got the balance about right. Having said that, I'm combing the wastes this time (to find all the bobbles) plus, I have bumped the difficulty up to Hard so I expect to hit the level cap way too early in this game.
Is it just me, or are the SPECIAL stats much weaker in this game than in previous ones? I get the feeling that there is a much heavier emphasis on skills and perks in FO3.
As far as the game itself goes...
The main plot wasn't too horrific. I expected better, but it kept me mostly interested. I only found 5 bobbleheads on my first run through (I'm up to 9 on my 2nd run including the ones that I haven't got yet, but know where they are from my first game) but I didn't do an awful lot of exploring. I'm wandering the wastes a lot more this time through. Giant Radscorpions are a LOT tougher than I expected. Every time I see one it's, "well, there goes another stim or two."
The side quests are very engaging, and have often held my attention well beyond the simple attraction of more loot + xp... I'm starting to dream in morse code, and I still can't understand it. Agghhhrrrr!!! Also, I have a feeling that there should be a way to finish "Pleasantville" in the main quest without butchering everyone but I can't find more than the vaguest of hints to its existence (I'm sure it has something to do with the musical items, but short of brute-forcing my way through permutations it has me completely baffled).
Anyway, this post is already longer than most people will read so I'll finish it here.