Just got to spend some time with the opendev and figured I'd share my thoughts and see what other people think. 

Overall, loving it. Really captures the feel of what made DOTE special but with more action and readability. Can't wait to see what's included in the full version. Ran into a couple of gameplay things I wasn't feeling as much:

• Hero upgrades didn't feel as satisfying as they did in DOTE. In DOTE upgrading a hero felt like it made them way stronger and often unlocked new or better abilities. It would be cool to see a little more of that. (maybe there's a kind of upgrading that I didn't find, all I saw were the terminals where you can buy new perks with food). Also maybe the meta progression stuff that's coming in the full version will satisfy this more.
  
  
• I don't know how I feel about having heroes that die auto-revive after a wave, but lose their items. Losing items feels too harsh as it wrecks any combos that the players had going in their run, but at the same time auto-reviving makes death feel like it's not that big of a deal. I feel like I might prefer if dying didn't make you lose items but it cost the other heroes a medkit or some of their health to revive you.
  
  
• Maybe I'm just a scrub but I find it hard to know what makes the different turrets better or worse than each other? I guess the goal is to put turrets that are strong against certain enemies next to their spawn points but that doesn't feel that interesting. I'd rather see turrets that add status effects like "electrified" or "poisoned" and then have guns or perks or other turrets that do more damage to "electrified" or "poisoned" enemies or things like that. I feel like some color coded keywords like this would make different hero/turret combos feel more obvious and unique from run to run.
  
  
• One other thing I didn't like in DOTE that seems present here is that you can unlock all these different turrets but once you know your favorite setup for each situation it doesn't seem like there's any reason to research or build anything else? I could be off base on that but was wondering if there should be a limit to the number of turrets you can build of a single type, to encourage diversity (or maybe build costs should scale up based on the number of turrets you already have out of that type). Maybe the first couple of turrets you build of a new type are even free? That way unlocking a new turret type would always add some value, even if it's technically worse than the turrets you already have access to.

I have the exact same feeling!

Upgrades are not as satisfying as in DOTE.
Ennemy, weapon and turret type is a bit mysterious for the moment because we don't have much information on what it does. A color code would be very nice.
And, as you said, I don't really see why I would need to research new turrets besides my favorite ones. But DOTE had the same problem.

Similar thoughts. Hero upgrades didn't feel like they changed enough. Basically they changed numbers. Some numbers/conditions I don't know what they do. That may be just experience with the game, I played a LOT of DotE (overall probably my favorite game of all time and definitely most pleasant surprise) so I knew exactly how everything worked, and knew what to expect from the randomizer engine. But in this version, I do not know 100% what 'operate' actually is, or the effects of wit. 

The auto-revive I am not sure I am at a point to offer an opinion. I kinda have mixed emotions, but I think I like it. It depends on if you get new heroes to recruit mid-mission and their frequency. It feels like it may be a placeholder, but could work depending on the design of the other mechanics in the game.

I totally agree on the weakness/element type in it's current state. It is not obvious enough to impact my decisions, and just straight up extra/less damage seems uninteresting. In DotE, each turret would target different bad guys first (based on the bad guys actions). So if I saw the waves on this floor were a lot of module bashers, I may go teslas instead of claymore/smoking gun etc. That felt more interesting to me, than just straight up damage. Also, the artefacts and research for the short bit we are playing isn't enough to really get diverse with turrets to research, so you kinda just pick a turret and go with it. Maybe later on in the game you may have a more diverse selection in your arsenal, but as you guys pointed out, with the costs of the upgrades that I saw to turrets, you may just save for those and stick with a small selection of turrets.

However, I will say in DotE, while I did have favorite combinations, what turrets I actually ran with many times depended on what was available to research, with some feeling more necessary than others (I will always have a shop on every run of DotE)

Just a couple more $0.02 from my perspective.

(All that said, I have enjoyed it quite a bit so far in my limited 6 runs and will continue to try to explore more and try different things)