I haven't been able to get very far into a V24 campaign because of crashes but I still gathered some thoughts on this iteration. I'm once again really pleased with how the game is coming together - with far less quirkiness than X1, this is looking to be a classic in the genre.
New UI
Great job with the UI rework! The soldier action UI is much clearer than before, and the best iteration so far. It no longer displays the soldier's flags but I assume that's just an oversight. Overall the understanding of what soldiers can do, and their status, is much better than before.
I would argue for removing the very common striped pattern from UI backgrounds, however. It's very noisy visually and doesn't convey the right thing to me, my association with such a pattern is "blocked", "not available", etc. As a purely aesthetic choice, I find it very weird.
One specific feature I'm missing is an indicator of whether there's enough TUs to fire my secondary weapon. Here's a fairly common situation - a soldier fired their main gun and has some TU remaining. Can I fire the pistol or not? As it is, I have to switch to the pistol to see that, it would be really nice to have some kind of indicator showing that it can be fired.
Many new tooltips in V24 deserve praise. I especially like the accuracy calculation tooltip, it does seem to have some issues but the idea is great and adds some excellent transparency to the game.
Combat / balancing
One point I'll repeat from V23 - demolition grenades are too effective. I think the numbers were changed after my feedback in V23 but they're just as effective as before, i.e. a demolition grenade consistently takes down an entire wall. They should be effective at making new holes in walls / cover, not large-scale demolition. Related, I disagree with the decision to remove C4, I think it's more interesting, and thematic, to have demolition grenades for small-scale stuff (blow a hole in the side of a building) and proper demolition chages (C4) for large-scale stuff or reinforced targets (UFO doors, blowing up an entire factory wall, destroying a small building).
I've been trying to make the HEVY grenadiers work but they're useless in the current iteration of the weapon. Normally the idea with that kind of weapon is that the area of effect makes it useful even with near misses. Currently, grenadiers don't even score many near misses - often the shot just flies out of the map, and sometimes they fall short of the target, destroying some useful cover or even wounding the grenadier. Basically, the gun is way too unpredictable now.
With the latest tech tree changes, there's now more options for production at the start of the game, which is good but I'd tone it down a bit. I think having too many options available on turn 1 can confuse players in a game that already takes a bit to learn, so it might be better to limit immediate production to just two options (move stun weapons to later?).
Other thoughts
Actual varied mission objectives are really cool! Abduction sites need a reward for rescuing extra civilians (is there one I missed?) but the concept's great, and I really like having a mix between Firaxis Xcom 2 style timed missions that reward aggressive play and the more traditional Xcom crash sites.
For the first scripted Alien Research site mission that pops up at the start, I'd add a couple Cleaners in there, just for the story, highlighting how Cleaners work together with the aliens.
The effect from adding more scientists (building a third lab at the base) is confusing - it does seem to speed up research a little bit but it's quite marginal and there's no good UI explanation of how much you're getting per scientist.
Technical note - could it be possible that the game's Unity builds have too much debug stuff turned on, or that the game logs too much? Even with a very good PC, load times are quite long, and I know that just enabling the dev build setting in Unity, which you need for stack traces in cloud diagnostics, doesn't normally add that much overhead. Not a big deal all in all but I'm a bit surprised at how long loading and even saving takes.
Will update if I can manage to get through a few more missions somehow.