Well, I hate to offend anyone right off the bat, but F3 isn't what it could've been. After I finished all 'easy' side quests and the main quest, I had no desire to pick it up again. Not even the DLC could get me to comeback to it's boring wasteland and the multitude of guns. That suck. Here are the reasons it didn't click for me.  
1. Wasteland... and then... more brown deteriorated buildings off in the distance. Ooh look a radio tower. Ooh a rock. Boring, dry landscape. The only thing I will give to this game about it's scenery is the whole D.C. area. While D.C. had, at least for me, some annoying travel routes, (I.E. FUCKING SUBWAYS) I always came away from travelling there with some new (interesting) locations. And Rivet City was one of the most original and innovative ideas I have seen for a major city yet, i'm afraid I can't praise the rest of the game's menagerie of beige.  
2. The overwhelming combat/lack of sufficient goods to fight in all these battles. Don't get what i'm saying? Let's say Jericho and I are going to explore the wastes. Deathclaw appears. That falls after some pretty good damage to Jericho, not to mention I had little ammo before the Deathclaw showed up. Next up is a Giant Radscorpion. I have no ammo, melee weapons are not a substitute for a gun. I die. Once I hit a high level, every combat sequence was ridiculous like this. I went around mashing RB so if something came up, I could either A. Run away, or B. Chance it. When option B worked about one out of every 25 encounters, I decided enough is enough.  
3. Using stimpaks. Ok, but using stimpaks to heal specific limbs so I wouldn't walk like I stubbed my toe on a rock? Bethesda, stimpaks were hard enough to come by, why the fuck would you force the player to waste one on a crippled limb. I'm pretty sure it doesn't even heal you if you use it on a broken extremity.  
 
I have many more reasons why I didn't like F3 nearly as much as Oblivion. But to contradict everything I just said, F3 had some good moments. Playthrough 1 was better than 90% of all other releases that year. Also I favor the story in that much more to Oblivion's immersive, but old-feeling folk tale of a story. The entirety of it's post-apocalyptia, mutant, science-y story was for sure, it's strong suit. 
 
I'll post a part two about everything in Oblivion that trumps over Fallout 3 sometime between tomorrow and next weekend. 
 
Comment! I love to argue about what I love. Action-RPG's.