I must say that I found the pre-alpha BRILLIANT, even addictive at this early stage.
You must have noticed a lot of comments said that the pre-alpha had a very battlefield-esque feel. I Agree, and that should be capitalized upon, but your game is NOT Battlefield, and I really believe that you know it, so you don't have to give in to all the requests for planes, tanks and the like, its a game about running with a rifle anyway
I do think your background music should be rather subtle to none at all since it keeps the atmosphere that is so enchanting in the pre-alpha, sound effects should be the main focus. I think bad company 2 did this very well, random planes flying, distant explosions, distant gunfire etc. The only problem is that having no BGM can result in a rather sterile experience, especially for singleplayer if the person is playing for a long time.
Next thing that I really liked were the trenches. Its a real pity that the pre-alpha did not feature more of it because they were great, the only problem is that you don't get that "last stand" feel in this kind of open-ended play. Then again, all of it is dynamic and the best moments are really "in the moment". However, I do think that you should have a different map with only trenches, and make it DANGEROUS to leave the trenches (i.e. mounted machine gun, ability to call artillery, gas attack, snipers...), that will be interesting.
For some reason, you game reminded me of WW1, maybe its the trenches. You might like to stick with that for the uniqueness factor (I have heard a number of people calling for unique or non futuristic/modern shooters) and ditch the automatics, that would also make melee more practical since you bothered to include it.
I guess its obvious, but can we have the option to shout commands consciously instead of only automatically while reloading or stuff, having the bots respond would be a nice bonus, I do wish I could say "guard this area" or "CHARGE!", the charge command would be fun.
Once again, thanks a bunch. Great potential, wish I could help you more but I am not very skilled in stuff like coding.