I was sceptical of the projectile shotguns at first, and still not sure changing them was really necessary, but one gets used to them and it works. It's even admittedly somewhat satisfying to kill enemies with the pellets, because of the visual feedback and 'having hit' through slight movement prediction. It feels hitting things is slightly more difficult now with the delay - at least it seems I've missed way more shots than I would have with hitscan, as if the monsters were lucky to zig-zac their way through my attacks.
The triple-barreled shotgun kicks ass. An actual improvement over the normal one, and good thing the maximum shell count is increased.
The plasma gun, like Shambler put it, just works, gets the job done. I can't decide whether it's an improvement over the LG and occasionally I would have prefered to be able to switch back to the LG as the plasma felt less powerful (possibly caused by restistances) and dangerous to my self at point blank range. At least it allows shooting under water (right?).
Axes are good, not as useless as the stock axe, and in many cases the axe upgrade is found quickly to make it suitable tool for emergencies.
The new and modified monsters are all very well designed and reasonably balanced. Some seem to have oddly little health while others have surprisingly much within their context (e.g. normal knights vs. crossbow guys). But it works out in the end, no Quoth-grade ammo sponges. Even the vorelings, although I wouldn't have minded if they had had even less.
Z-aware ogres are a bit of a mixed bag. Generally, I think removing their grenade limitations is good and adds to the gameplay. At the same time, the z-awareness can make it quite unfair for the player occasionally. Seems to be as if at short ranges the grenades are very fast and harder to dodge. Glad they have a range limit, too.
Zombies, on the other hand, are still unable to attack vertically. Maybe it's for the best, though.
One thing that bothers me a little is how some of the modified monster models, especially hell knight and ogres, are so thin in their posture compared to the originals.
Knights and zombie knight models, while being good overall, could've used a little touch-up perhaps. Something about them feels wonky to me, maybe because they are so round now?
Same with the updated shambler model. He has been working out obviously, but his death animation is a bit of a diva move...
The monster spawners are tricky. They add tension to the gameplay and a further component of target priorization which is good. However, mappers must be careful not to let this get out of hand. YES, YOU, IONOUS! :) Depending on the situation, this can cause ammo shortages. Most maps handle it well, or at least it worked out for me in most cases, secrets and respawning items etc.
The scrag queen is cool if not slightly overpowered. Or maybe it only felt that way, because the arena in Zendar is fairly small and dead-endy in terms of cover with regards to the additional mobs. You should have added the scrag boss from Travail as well -> scrag kind and queen in a scrag kingdom
map with a permanent flight powerup. Hmm, looks like there's now way around AD 2.0 now!
The resistances to certain weapons didn't really look clearly communicated to me. There's mention of particles indicating resistance somewhere here, but during the game I didn't recognize what does what. The only obvious thing is grenades bouncing off certain enemies and rockets seemingly flying through scrags. Not sure I like the latter in particular. While in theory a system like this can add some flavor to the gameplay, I think in Quake, at least for me and in this mod, it's largely irrelevant as I just keep shooting until the monsters are dead unless it's clear they don't take any kind of damage from the current weapon.
I had some thoughts on each map, but can't really recall. Let me just repeat what other have probably mentioned and say the maps are amazing. Great detail, many secrets, so much to explore. The rune meta game is a nice touch. Ever so slightly intransparent, but rewarding if completed with a stunning credit map.
Newschool stuff like skyboxes, fog, colored lighting, alpha textures and (excessive) particles was used to great effect. Made things look fresh and modern, yet still sufficiently Quakey. As far as I can tell the new map functions add a lot of potential for unique designs and gameplay/story/event opportunities, much of these probably yet to be explored.