OK, time for the newb to put pen to paper, or more appropriately, finger to keyboard.
What I personally would like to see is some of that 80's heart, I agree with Stinger78 that it should capture the magic of movies like Conan and Beastmaster (which I know was pre-80's, but still). I think that He-Man should most definitely have muscles that most people can only dream about, because really, that was part of the awesomeness of the characters and the action figures.
I believe that they should keep the humour natural and well written, without trying to force out purile and pointless humour wherever they can. Keep it clever.
The heroic characters as well as the baddies need to have their flaws, that is what will make them interesting to the non-fans.
Sensible use of CGI would be great, but this does NOT need to be Avatar (and hence should not need a 2 billion dollar CGI budget). Use it *only* where needed, ie. Battlecat and Orko.
An intelligent use of a "cameo" moral lesson would be fun... but it has to be subtly done, and mostly for insider enjoyment.
Please, for the love of He-Man... let's NOT find out that Teela is his sister...
Lastly, keep Michael Bay at bay... if he wants to direct this I want a show of hands for an assassination attempt, ok?