I picked up a copy of the RPG and PDF but I have not read it in any detail yet. I did find this information on their blog.
We could have simply repackaged the second edition of M&M with DC art, examples, and sample characters, but if we were going to produce a new, stand-alone game product anyway, why not take this opportunity to tune-up and spruce-up M&M? It was time: the second edition is five years old and, while it has been solid, there are things we've wanted to fix, either known issues with the rules (like ... sigh ... grappling) or ways in which we could streamline and simplify. We also had the benefit of years of supplementary material and insight, particularly Ultimate Power, to work with.
Much more versatile, mostly due to lifting most of the restrictions; also, renamed Grab. In summary:
Standard action to Grab victim.
Grabbing effect (Strength or powers) resisted by victim's Strength or Dodge. It's a bit unclear, but it seems that the attacker's effect is a 'routine check' and that the victim is simply trying to resist it as normal (DC 10 + rank).
If succeed then victim gets basic conditions, with degrees of success mattering, and you get "hindered and vulnerable," and that's round one.
Free action to maintain.
Take turn as normal, remembering the condition effects.
Can move victim with you, he can resist with his Strength vs your 'routine strength' (take 10) check.
Victim can use Athletics or Sleight of Hand vs. Routine Strength (move action) to escape. Free move up to -1 rank of ground speed (1/2 speed) upon success.
The biggest change is that there is no longer an exclusive list of what can be done in a grapple. While that is much simpler, the lack of explicit bonuses about the Strength check for Grabbing does leave some room for confusion.
I've been mulling over Impervious. At PL 10, ignoring damage 5 isn't that great in a real knockdown fight. On the other hand, the new pricing kind of fits, comparing Immunity (Damage) to Impervious 20. So perhaps Impervious should simply be decoupled from Protection and made into an effect.