Playing the MW4 free release is what led me to MWLL. I had never heard of the project before then.
What I miss most from MW4:
- Being able to look around. I don't mean 3rd person, I mean the equivalent of mounted external cameras to look left, right, and back (or the view through the window in mechs that have greater fields of view). I think a direction-of-travel view would be nice as well. I'm not in the military, but I would think these would be pretty obvious features to include in any war machine. Having the ability to aim arms separately was pretty nice as well.
- Allowing shift, ctrl, or alt to work as modifier keys (I don't expect this to be implemented). It's nice to have more options under your fingers without having to get your hand out of position.
- Lower graphics options for better frame rates (I don't expect this to be implemented). Yes, I know, my system wasn't meant to handle Crysis, but I would willingly give up a little more eye candy to always get 30+ fps. Someday I'll be able to justify a better system, just not right now. From playing around with settings and such, it seems that some of the options are controlled by the server, and that others simply depend on how the mod/map is built - I could be wrong on this though.
As for the MechLab, I think that the combination of (1) allowing servers to limit/disable the MechLab, and (2) having a cost multiplier that goes up as the customizations get more extensive are two very good ideas for keeping it from ruining the game.
All in all, MWLL is a great advancement considering the various assets that can be played, which is what initially attracted me to it. Sure, MW4 has BA in it, but it felt more like protomechs to me.
MW3 was great, more enjoyable than MW4 to me, but sometimes I still hear the "music" from the original going through my head when I make a kill...