So, what is so bad about these two games in a bullet list rather than wall paragraphs. Links to examples are fine.
Fallout 3:
- Abysmal main quest, both in terms of structure and writing
- Generally dodgy writing across the board, though if you like weird surreal shit, you'll find a thing or two to interest you
- Bad combat and RPG systems (if you played New Vegas, it's the same as that, bar a couple features like ammo types that NV added)
- Dungeons are a very mixed bag, mostly bad, especially the metro systems
Fallout 4
- Virtually no content - few quests (and they're all terrible), literally only one notable settlement
- Tedious settlement building mechanic which is simultaneously totally avoidable and also central to the game thanks to the loot system
- Forced to gather shit to upgrade your weapons just to deal with the enemy health bloat
- New critical hit system is the stupidest thing ever in a videogame
- "Legendary enemies" that are absolute shit
- Subjective, but I think the game looks hideously ugly and the generic art direction makes it look worse than either Fo3 or FNV
To say a couple good things about each game:
Fallout 3:
- Good quest structure, often with creative solutions and consequences of the kind you can't really find in any other Fallout game
- Skill checks are usually percentage-based, rather than New Vegas's shitty fixed ones
- World looks very nice due to strong art direction, though you may not like the green filter
- While dungeons are mostly the usual copypasted shit Bethesda's always done, there are some very memorable and unique ones
- Radio is great, especially if you kill Three Dog to shut him up
Fallout 4:
- Combat mechanics are a step up, though again, not by much
- Weapon and armour modification system is fairly expansive, if you're interested in it
- Some of the city-based areas are nicely vertical and let you go bouncing around on rooftops
- Some of the perks are interesting (but a poor substitute for the old system)