What are the biggest issues with it?
I never played MWO, and I haven't actually played ANYTHING in the Battletech universe in over a decade now (I'm going to ignore PC Battletech for purposes of this question). However, I really liked MW4 and earlier, and I spent a good chunk of my tweens and teens playing tabletop Battletech and pnp Mechwarrior. I've got brand nostalgia, but I'm not current by any means, and I'd probably be willing to play something at least as functional as a twenty year-old game, especially if there are any plans for adding VR support (are there?).
Also, am I correct in assuming there is no Clan presence in the game? I am a basic bitch who loves his Timber Wolves, but I'm happy to settle for a Warhammer if Clantech is not present.