Absolutely! Considering you can probably get it for 10$ right now, I'd heartily recommend it if you like anything at all about the Mechwarrior universe. The campaign is a fun straightforward mission after mission setting and although they could have made much more out of it it's still one of the better xbox games I've played as far as fun factor. Mech Assault 2 looks to be much much better, IMHO.
i'd go with mw4 if i could get to work on my computer but for those days of nastalgia you just gotta go with MW2 and MW2:Mercs <sigh> nothing beats those. MW3's pretty good but i didn't like the fact that blowing off a leg would completely destroy a mech cuz it made for some cheap tactics by other people.
mech 4 should have stuck with the mech 3 interface, the controls for mech 3 were bad ass, hands down. mouse controlled tracking arms, sweet stuff. i also didn't like how 4 limited you to the customization of your mechs weapons. should again have retained the earlier series setups, and made it so the weapons showed up differently on the mech depending on how you configured it. but, i'll say this. mech 4 mercs was fun as hell, even if mech 4 overall was dissapointing in how they set it all up.