Y'know, I may not be the best commentator on these matters, but I'll say a brief piece anyways.
I really wasn't grabbed by MWO when I first tried it a few months back. I've only got room for so many grindy F2P multiplayer games, and MWO just didn't strike me as generally "good" enough to warrant making space. Yes, the presentation (graphics, sound, etc) is quite nice, but I found the frontend main menu confusing and unintuitive, and the gameplay felt very similar to old MechWarrior titles I've played previously. Having now gotten my hands on MW4:Mercs, I think the latter is the superior game even before considering dev antics, of which I'm admittedly not very clued into.
It's a damn shame really. Genre fans have been really hard-up for a good stompy robots game, and watching MWO's saga is nothing but disappointing. Perhaps I should look into Living Legends, or maybe I'll just stick with Mercs.