I've been playing Fallout 3 since it release and finally finished the main quest. I still have lots to explore but wanted to finish the main quest and play some new games for a bit before going back and looking around. As a fan of both the old Fallout games, Bethesda's other games and PostApoc stuff, it would be hard for me to not like this game unless it was really bugged or broken. I happily played this one for 41hrs with minimal mods and ended at level 17.
I at first was going to avoid this game due to my old rig but other posts mentioning their systems and the game's min requirements encouraged me to get it. To me it ran as well as Oblivion did on my ol' barton 2500 OC'd to 3200 w 7600GT and 2GB RAM. Save and Load times even seemed quicker. I had only a few crashes compared to the gnashing of teeth I've read about. The few I had occurred when I had one of the radio stations on while entering a load zone so I left that off. Main trick was getting the game to run on W2K, which I did using previous tricks I've learned (Edited DLLs) and help from Win2KGaming.
The PostApoc setting is a nice change from the normal D&D style stuff. While Stalker was more of an FPS with a few RPG additions, F3 is more of an RPG with FPS additions. As many said its Oblivion with Guns, which I don't take as a bad thing though it was meant that way. While OB took many a mods to make the game more fun (Get rid of autoleveling, etc.), the only mod I used in F3 was to the HUD to make it less consoleish (MTUI Hud Mod).
While some of my ingame fighting was done in the usual FPS style, I normally used VATS. Being able to pause and target was nice along with the bullet cam that goes with it. It also helped to get of a nice amount of shots at close range before the enemy could get at you. While I did some non VATS combat, the characters move a bit jerky. Its sort of the issue that all these RPGish FPS style games have where the stats based combat don't mix well with real time. This is one of the better systems though since others just have jerky FPS combat without the pause ability to go turn based.
Main weird design decision I found was how close one of the larger cities (Megaton) is to you starting point at Vault 101. I think it would have been better if you had to go through some smaller communities first before hitting the big city. I figure its that close to help people new to this style of game who would have got tired of scrounging to survive for a long stretch before getting anywhere. Also, while in OB I used the quest arrows mainly as a time saver, in F3 I don't find them as odd since I just assume its part of the Pipboy helping me to navigate.
I never had issues with the lengh of the main quest though as I spent a lot of time doing Moira from Megaton's survival guide quests. While doing these I'd run over the hill to see the next site when something caught my eye. Once I did decide to finish the main quest it did go fairly quickly, but I had already explored a lot. The game does seem to balance those wanting a quick game and those wanting a long game well. For those wanting a longer game just spend more time on side quests or randomingly exploring instead of plugging away at the main quest.
The game does have a lot of scenic moments though. I had tons of screenshots to sift through to find the ones I really liked. I'll probably post some others as I do more adventuring, which I plan on doing for OB and Morrowind, once I go back to those to explore more or finish up their expansions. Someone either needs to make a Wild West or Steampunk mod.