Here's the interactive skill tree for the Mechromancer. http://www.borderlands2.com/us/skilltree/mechromancer.html
They did say that she was going to be the most powerful character. I don't see how... Basically looks like a dumbed down commando mixed with an even more dumbed down siren. Personally I don't see anything really drawing me in to play as her. I'm sure she'll be pretty powerful with all/max skills but the Siren will still reign supreme as always. -_-
She looks good, but it seems like it's more Deathtrap damage then her own self. Siren is an all out death machine. So. It'll be good. But Siren will be better in my opinion.