Well ... after leveling one character to 50 and another (better) one on the rise, I think I'm ready to render a verdict.
Pretty damn good game.
A few general thoughts:
* No VATS grenade-hucking! BOO HISS! (I've also been finding explosives underpowered, generally.)
* Survival mode, theoretically super-hard, is too easy. It starts off really rough, but if you have any meaningful synchronicity among your perks it gets way easier in a hurry. Admittedly, that's with a stealth build running solo so that I don't have any allies to screw it up for me.
* On the subject of perks: certain builds are horrifically unbalanced. I've been running a stealth gunslinger type with the Deliverer, the Railroad's unique 10mm silenced pistol, and the little thing one-shots most targets (the Sandman perk is a must if you use silenced guns-- it's how you build up stealth gun headshots to be a match for stealth melee). What it doesn't one-shot, it minces with multiple sneak attacks. If you take Concentrated Fire, you can build even a 1% hit chance (due to distance, not cover) into an easy kill by burning the better part of a clip downrange. It is now the only weapon I bother to carry. You can do much the same thing with a silenced, VATS-enhanced tactical hunting rifle; just optimize for VATS efficiency and save that blingy marksman stock for the rifle you actually snipe with.
* The Penetrator perk is initially disappointing (I briefly got the idea that it just plain didn't work) until you realize that while it doesn't just let you shoot through walls or even a few things it seems like you should, what it does let you do is horrifying. Like, line up enemies, aim a headshot at the last in line, and watch everybody keel over. Or casually blow the usually nigh-unhittable fusion power core on a sentry bot with a single pistol shot. Or blow the face plate off a mirelurk from behind.
* The enemy burrowing/teleport/instant detection mechanic: awesome and fun when mole rats do it (pistol-based whack-a-mole!). Horrifying (at first, good), then frustrating (bad) when legendary albino radscorpions do it.
Having something fragile able to pull those kinds of shenanigans is one thing; an armored melee nightmare that I can't get out of melee with is something else again. It's pretty cool having something that makes me actively look for a rock to stand on, but less cool when the damn thing shows decidedly super-arthropod intelligence by realizing that it can't reach me, I can hurt it, and therefore it should hide until I set one goddamn foot down on soft, diggable ground again.
Add the Legendary instant-regeneration ability and you've got a seriously problematic critter. This is the sole exception I've encountered to survival mode being too easy.
* I wanted a New Vegas-style survival mode, but that would get pretty pointless with all the homesteading you end up doing.
About that:
* I initially didn't give a damn, but it does do a fine job of making me feel invested in the game. Local Leader is damn near mandatory and (therefore) should be MUCH easier to acquire.
* Expanding settlements as fast as Preston wants you to is actually a bad idea. Better to take it slow and fortify things properly as you go.
* Missile turrets: So. Worth. It.
* ... On which note, I wish the silly system wouldn't keep giving me "help defend" objectives and doing HORRIBLE things to my settlements if I don't show up, considering that showing up usually means standing there and twiddling my thumbs while listening to raiders dying in volleys of rocket fire. I know it's not set up to properly run battles in my absence, but low level enemies against even one missile turret is a slaughter. So far even combat armored Gunners get reliably dismembered.
On the plot:
I've seen some complaints about the lack of a karma system and factions (outside the raiders, supermutants, and other always-hostile "hazard" factions) you really want to kill. Essentially everybody you can side with has some good points, some bad points, and some good people working for them. However, the factions are at loggerheads and at least one, probably two, will just have to go ... meaning, everybody dies, including people you like.
I actually like this change. Considering the game's "war ... war never changes" postapocalyptic theme, the good-versus-evil structure was always inherently hypocritical. You can't very well go make a story about the tragic aftermath of nuclear war and then make it "okay" to (often literally) nuke all the bad people. Ultimately, a lot of who you end up siding with, whom you define as "good" or as "evil," depends on your beliefs about some pretty arguable and complicated issues, not on who's nice and who isn't.
If you take sides sufficiently to see it through to the end, people who probably don't deserve it, who might even be your friends, will die. Too bad. That's war, and war never changes.
Right on. Well goddamn done, Bethesda.
For the record, I ended up siding with the Institute for my first playthrough. The Railroad has a point about respect for sapient life and the Brotherhood's probably not wrong about technological hubris, but I'm NOT about to blow the Commonwealth's equivalent of Isaac Asimov's Foundation to perdition just because the rest of the Commonwealth is scared of them.
... even if they do have an unfortunate habit of trying to strip the Commonwealth for parts.
... and they forgot to institute all three Laws of Robotics.
... and they haven't quite worked out that there's no meaningful difference between people they've created and people they didn't create-- there are definite signs that they're picking up on that, though.
... and there's that whole doppelganger program they've got going.
Okay, so they're legitimately scary. I'm still not about to just kill them all. Besides, that teleporter is really useful for saving time on settlement defense.