Well, since everyone is jumping on this bandwagon.
First, let me say that having played MnM I have to say that I honestly like it. It is a tight system. And I think it speaks to it's economy of design that it does rather well in 192 pages what most games can't do in twice that much space.
Keep in mind, this isn't D20 Champions. It's streamlined to a different degree.
Now, having said that, I'll say that I still prefer the uber-flexibility of Hero. In my opinion, this is both it's strength and it's weakness to the average game player.
Comparing the two, I think that I've boiled down a list of where I believe Hero could improve.
First, a better set of pre-built powers complete with optional extras that can be tacked on. I've noticed that people enjoy just picking a power and doing a general tweak, as opposed to building it from scratch. And it makes character generation so much quicker. Yeah, I know some of you out there aren't fans of the spoonfed method. But apparently, there is a market of uncaptured players that are a fan of said method.
I understand that Steve is working on such a book. It can't get here fast enough.
Second, combat, combat, combat. I've seen both rule sets have combat suck and drag. Part of it is due to complexity, part of it is due to inexperience. For instance, my one friend (I have two ) can run the combat as fast as any system I've seen. Then again, he's been playing for almost 15 years.
I would love to see a FAQ annotates a medium-sized combat (5-10) people put up on the web site. Something that can walk someone through actions, the speed chart, END, REC, where some optional rules might come into play, etc. And like I said, annotate it. Put in some design notes, why some choices were made, and page references in FREd.
Well, maybe this is just wishful thinking, but I know that it would help the morons that I play with.
To end on a positive note, here are the things that Hero does extremely well. Out of the box, it's great for multi-genre play. As we all always point out, it's infinitely customizable. Limitations work in a much more balanced way. It's more internally consistent.
Though, it's a lot easier to carry around the MnM rulebook.