- Operation Anchorage: it is just a standard shooter thing, and Fallout 3 is not a great shooter in the FPS sense of the word. Plus, it gives you two of the most overpowered items in the game, the Chinese Stealth Armor and the Winterized T-51b Power Armor - the latter doesn't even get damaged and ruins the whole idea behind the Power Armor perk.
- Mothership Zeta: more shooting, lots of shooting. Its setting has nothing to do with the original game.
- The Pitt: it doesn't really add anything meaningful to the game. It is just another subset of quests, but at least it is reasonably interesting and follows the spirit of the original game.
- Point Lookout: the best add-on of the pack, with a new and mysterious (even scary!) area to explore and some interesting quests, even if some of them are B-movie material -- but then I guess that was the idea.
- Broken Steel: perhaps the most disastrous add-on of the pack, it changes gameplay for worse in various aspects: a) the new level cap doesn't really fix the problem of getting too much XP too fast in the previous levels - it is just a way to satisfy those who wanted to hear the 'ka-ching!' sound after finding a new place or killing an enemy; b ) it makes the ending even worse than it already was, because it doesn't extend the main quest - it creates another one, a fairly uninteresting string of shooter sequences; c) it adds enemies so powerful that the whole thing becomes ridiculous, really: you cannot walk five steps in the wasteland without stumbling on Albino Radscorpions, and the Super Mutant Overlords add insult to injury, because they are present at lower levels, making some quests unnecessarily hard - Germantown Police HQ, anyone? They are just bullet sponges and do not add 'challenge' to the late game.
To me, the original game had a better balance than the final game with the DLCs. It had powerful but manageable enemies (Deathclaws and Super Mutant Masters) and I liked the fact the game would eventually end, prompting me to create another character to explore areas I never visited with my first character.
Although I like some things from the DLCs (particularly some quests) I think they just kinda ruined the game for me. That's why I'll go back to the old vanilla game in order to experience Fallout 3 as I think it should be played.