The Mechwarrior series are part simulation and part FPS, with emphasis on the former. The meat of the game is customizing your battlemech before going into the game. Should you fail, then chances are you're not using the weapons at your disposal effectively. This is why Mercenaries' nonlinear campaign works so well.
I'm pretty sure the difficulty curve is more fair in the campaign than if you just jump online. The difference is that you don't have to buy the 'mech or weapons first in order to build them, and that the difficulty is dependent on the participation or bots.
I've been playing it since MW2 so I'm used to using the full keyboard to control the battlemech. Give it a shot anyway, just don't go in there expecting to play a Halo lookalike.