My first impressions are great, though the camera can be a little janky.
Selecting the correct tile is just as awkward as the first game, which is a bit annoying too.
The timers seem to work well. You're not 'rushed' like Valkyria Chronicles or whatever.
You've got plenty of time to advance carefully, you just don't get to do the tedious "move/reload with one guy, overwatch everyone, end turn, repeat" dance.
It makes for interesting choices about whether to spend a turn reloading/consolidating, or whether to push on. You have time to set up ambushes, explore and reload - but you won't be reloading everyone just because their magazine isn't maxed.
The sectoids are bastards as always, and the commanders seem pretty accurate on veteran (though I have a small sample size so far!).
Lost a guy on the first mission because the commander hit him twice while he was behind heavy cover (and at extreme range on the 2nd shot, since I had him retreat).
Oh well, that's XCOM baby. Plenty more grunts in the barracks.
The Long War mods seem good, though I've only been able to experience the SMG one so far. I'd advise everyone to activate them. You can always just not use the SMG (and probably officer promotion) if you decide later that they're crap. The muton commander thing looks like it'll add some challenge to the late game.
The SMG gives you a +3 speed buff (goes from 12 to 15), but does 1 less damage and has 1 less mag size than the assault rifle. I think it also lets you get closer without breaking concealment.
That seems like a good balance. It's definitely not overpowered and IMO the rifle is slightly better in most situations on veteran. Losing 1 damage means no guarantee of 1-shotting an advent grunt, which is a big deal in the early game. The higher tech SMGs might be better though, and it'd be good for scouts (and a pistol-based sniper/gunslinger might be viable?).