I have run about 5 hours of just plain encounters (with a couple friends for play-testing) and another 3 hours with a full group of players. I DMd the whole time.
I like it from a DMing aspect, I love minions, LOVE THEM. they are a rules abstraction, but they do damage, they are dangerous, and they help the baddies tactically. I also think they make players feel more heroic.
Too many minions may be unbalancing to the party, I don't think you should use more than 2.5x PCs. if you have 5 I think 8-10 minions with 3-4 normal guys is about the most you can use without danger of impending doom because your wizard missed with scorching burst.
really if you never have more then 4 minions per normal monster, and you stay in the encounter design XP range you should be fine.
Sleep is still an encounter winner, it pretty much owned the elite that we fought. slowed him so he couldn't get to us, then he fell asleep, and everyone surrounded and blew their highest damage abilities on him while he was prone. then he stood up, took some AOOs, and got tripped by the fighter the next round and damage ensued once again.
The rogue is excellent, but his damage didn't seem outlandish for a striker, the other strikers (from the D&D exp) do comparable damage to sneak attack (less, but not massively so) however they don't need to have combat advantage, and rogues can only sneak attack once per round.