Well, as for mech legs, I think they're pretty great.
Pros:
Really sturdy.
Unlike other movement types, if you lose one on the on side, you're still pretty good to go with your other leg, if a bit more clumsy.
The focus on being vertical means that you have an easier time placing electroplates.
While they can't climb everything like a spider bot can, they are pretty good at climbing slopes that a ground hugger would have a fair bit of trouble with, plus they can jump up what they can't climb.
They can do a decent crouch which is good if you want to hide them behind cover.
They are also really hard to tip over, really, the only real way you can pull it off is by jumping off a cliff and colliding with something on the way down.
Cons:
If you get temporarily unbalanced (or lose a leg) then you can spend a second and a half stumbling around like a drunk idiot.
While they are really sturdy, they are also really exposed, so if a rail or plasma hits you right then it's gone.
I'm pretty sure they are the slowest movement type we have yet.
They tend to be the tallest bots running around, so if you didn't place electroplates right, then you're toast.
For that matter, they pretty much /must/ have electroplates as they are getting shot the most.
There's also a sound bug around them that is endlessly irritating, chittering and going shick and click.
There's also other stuff I'm missing but I think mech legs are great.
Hey look, here's my Stomper.
It can take a lot of punishment and keep going, death typically coming from all my stuff breaking instead of losing the cockpit.
I have yet to die from a cockpit death actually, from rails or otherwise.
The shoulder thrusters are there for reasons.
Of course, there is a lil' man in the round belly.
It also has butt-plates for reasons.
So far it's the only thing I've made that does really well.