Some thoughts

[NeverDT]

1. I don't understand what the point of stamina is, at least the way things are currently. All it really does is limit sprinting - I've never had an instance where stamina prevented me from jumping around or doing melee. However I think it should also be feasible to rush through areas (at whatever cost) and if anything, the amount of stamina available doesn't let you get very far (although sprint slide ninja jump combos help).

2. I do like the idea of stealth, but I also foresee timed missions (beyond the occasional 5 minute "get out" timer), and if that's the case, you're not going to want to stop and fight everything or slowly creep through the level. This is one of the reasons I hate Corpus so much. Speedrunning levels should be possible (after all, this is an uprising and we're playing for objectives, not necessarily rampages); also, it'd be nice to have a crouch sprint.

3. Guns are too inaccurate. The dual Latos are the only gun I've used so far that has a reasonable amount of accuracy at range - I use the Burston and the Sicarus, and I just picked up the Gorgon. It's a pain to hit anything, you do crap damage if you're not aiming for the head because of heavy armor on so many enemies, and even then when you're aiming for the head you're just as likely to hit the body or miss entirely because of how far shots angle off the crosshair. I assume the Snipetron hits what you aim it at, although I'm afraid to try the Latron. This was one of my biggest gripes about BL2, a general lack of accurate weapons and enemies having a definite edge against me at close range. With Corpus and higher level Grineer, they also have an edge on me with how many shots they can put out (especially given how many of them there are in any given area). Although that last one is on me since I play solo a lot. Die, coop bugs!

I'm interested to see where this "cover animations without a cover system" idea goes, and I think it'd be something very fitting for this game. I fear that a cover system would lead to boring extended gunfights a la Mass Effect on Insanity and cut out melee and close range abilities entirely. On that note, please please please don't make abilities useless in boss fights and please don't make certain frames useless for certain enemies.

As for PvP, I've seen it discussed in other threads, but I think it boils down to one thing: This isn't the game for it. I can tell you from having been involved in Firefall that the devs went through a lot of consideration on how to balance PvE with PvP, ultimately deciding to separate the two. What comes of that is neither here nor there, but I think Warframe will turn out a much better game if the devs focus on a coop game unbridled by the significant balancing PvP demands.