Alrighty, I just got done with Doom 2's vanilla maps as all classes with this WIP version and here's my report:
One thing is for certain this is a massive improvement over the previous versions in terms of looks and functionality. I know this is still a WIP, but I am going to go over everything that needs addressing.
CLASSES
1. Marine - The game as it is now is in the Marine's favor with all of the goodies laying around the map. Other classes don't benefit from pickups at all except dead Preds dropping weapons for the Pred class (yes I know I am stating the obvious.) Essentially the Marine is a glass cannon, he dishes out tons of damage, but can't take a hit. This is a bit of a problem as the Marine is a bit too squishy for the vanilla map set, lots of save cheesing is needed to progress. The explosives the Marine has access to can easily kill him if he isn't careful, but often times he takes tons of damage from them even if you stand at a reasonable distance.
2. Predator - Fresh starts as a Pred can be overly difficult due to only having your wrist blades to fight with til you can kill an enemy Pred for its weapon. This is a major balance issue pending on what kind of map set you pick. However once you manage to acquire some weapons, the game goes from really hard to really easy. At level 10 the Pred is unstoppable and little to no strategy is involved in running over everything you see, even on the hardest difficulty.
3. Praetorian - Using the Praetorian is like starting as a level 5 Predator, you can mow through lesser enemies with your claws and tail stab the bigger ones. It got quite dull using the same strategies over and over to get through the game as the Praetorian's kit is severely lacking in variety.
WEAPONS:
1. Marine - The Marine's arsenal is pretty strong, though the weapon balance could be tweaked. Everything that uses bullets (except for the pistol) did a bit too much damage. Smartgun in particular was literally the god weapon

. The shotgun was totally outclassed by the bullet weapons, I only pulled it out on rare occasions. The pulse grenades and the rocket launcher (S.A.D.A.R.?) were really hard to use due to being overly careful not to blow yourself up. I would be standing 20+ feet away from my target and manage to instantly kill myself with those 2 weapons.
2. Predator - The weapons got OP after like lvl 5, save for the spear gun, that thing was really weak except against zombieman variant spawns. At level 10, all you needed was the wrist plasma launchers because they pretty much 1-3-shot kill everything.
3. Praetorian - Not much to say here, the claws and tail are pretty standard (and did nearly the same damage.) Though it is still missing a lot of potential attacks such as the head-biting, the ramming charge, and the Goomba stomp.
CONTROLS:
I noticed the control layout was similar to how AvP functions where hotkeys were sharing functions, which is fine. But some functions could be consolidated by mapping the hotkey as a press and hold function or a double tap. Super jump for instance, that could be made to be used by pressing and holding the jump key instead of a hotkey toggle. If you are unsure how to do it, check out Project MSX, that has a bunch of multi key functions.
SUGGESTIONS:
1. Rework the damage numbers on everything so it doesn't become an insta-kill fest throughout the game at one point or another.
2. Fix the explosive weapons so they don't cause so much self damage.
3. Reduce the Predator's progression rate and reduce the power gained from it.
4. Allow the Predator to start with a full ammo Speargun to assist with the rough fresh starts.
5. The Pred's Wrist Blade uppercut and the Praetorian Tail Stab should be changed to a charge-up attack to deal its full damage like it was in the previous games.
6. Pulse Grenades were too rare to come by, maybe they can have a rare chance to spawn where health and armor bonuses spawn.
7. Not sure where you got that menu screen pic from, but something seems off and very unsettling about that Predator's face

. A different pic would be better IMHO.