Originally posted by Sandwich
Actually, fiction aside, if they ever get a real mech-like combat prototype working like it should, it'd be quite an amazing piece of work. There's nothing like appendages with which to climb over obstacles, and the armor and weaponry level is purely dependant on the strength of the leg material. Honeycomb/bird bone it, and you'd have a sweet setup. 
Ah, the old 'mechs can carry as much as a tank' argument. I've seen it before.
Alright, so you have your sixty ton mech, same weight as a tank. How big do you think it'd be? Ten meters tall? Fifteen? Assume it's the same width as a tank.
That's a hell of a lot more frontal area. Sure, you might has thirty tons of armor like a tank, but it'd be spread over a much wider area. For a vehicle that weights the same as a tank and presumably is supposed to serve the same roles, you'll have something that is
far more vulnerable to heavy weapons. At the same time you have some sort of main gun, which is placed on the arm, I suppose. So you'd have an extremely high off-centre recoil which is acting against a, relatively speaking, flimsy piece of vehicle. It'd be like firing a .50cal sniper rifle one-handed. BAD idea.
Furthermore, running is a less efficient motive form than rolling, and requires more moving parts, which means weak spots and maintenance problems.
So, what do you want to use this for again? Crawling over rubble? Seems rather overspecialised.
Sorry, but when you bring realism in, mechs are not effective. Impressive feats of engineering yes, useful combat vehicle no.
