it’s been multiple eternities since I’ve played 3 or NV. 4 I’ve played more recently, but that was … basically when the last dlc dropped? So… memory of those games not really the sharpest.
London is mechanically almost identical to 4 (duh? because mod, duh.). The parts of the main-story I’ve done has been great. I recall preferring side and dlc missions over main-plot in 4, but I was pretty into the main stuff (dlc or not) in NV.
some thoughts about it in no specific order:
I’m around 20 hours in, and it feels like I’ve only started. Plenty of map markers opened, but VERY little of actual land area explored.
there seems to be less emphasis on settlements, haven’t had a permanent residence (storage, bed) so far, been storing my junk in some friendly town crafting stations which don’t seem to de-spawn stored stuff (as tipped in the mod’s discord).
but settlements are apparently still a thing (not sure how I feel about it, they were the worst part in 4, imo) - haven’t aquired a settlement yet.
it’s bit more difficult than 4, ammo is a bit scarce and some enemies are ridiculously tanky, even at normal difficulty.
the early game can be a bit brutal, but eases off as you get levels (ref: at ~10-15h or so in, I was finally able to take enemies down with confidence)
The city is HUGE and dense (requires some more grunt from the computer than base-game), there’s things to do and see in every corner, a lot more buildings to enter.
“level design” is mostly great, but there have been places where the route forward/mission critical progression item was hidden by all the clutter and generally darker lighting.
the level design also contains surprisingly deep puddles here and there on the streets, and those build up radiation QUICKLY. Bodies of water in this game are dangerous.
Food and other non-stimpacks seem to be in quite a big role, at least in early game. IIRC fallout 3/nv/4 basically showered the player with stimpacks.
Voice acting is pretty good, if a bit hammy at times.
I recall enjoying all fallout games, some more than others. I mostly mod for convinience (eg. busywork, carryweight) so I’m not really playing the game(s) as intended. And this one is great… if a bit buggy here and there - but not any more so than actual Fallout games. :D
I totally recommend London, but it comes with an asterisk: the mod requires tweaking, and depending on your computer-skills it can be either “man, this is obvious” to “wtf am I doing”. Config-file editing and extra mods are required to get it actually working. Def recommending Mod Organizer 2 as well. Also, if your base fallout 4 (and dlc) are from steam, you need to downgrade from the “Next gen update”. I’m fairly sure there’s good step-by-step how-to’s to get it set up at this point.