It's quite simple. With the super-sub, they should either get rid of it or allow teams to name them after the toss. It's ridiculous that you have to name your sub BEFORE you know if you'll be batting or bowling first. That's just stupid. I think they should name their 12 before the toss and pick a super-sub after the toss.

With the power plays, they should definitely make a change there. It's BORING at the moment. Either allow the batting team to pick one block of 5 overs or make the bowling team choose one of the two blocks of 5 overs in the 2nd half of the innings (after 25 overs). Or to make it really interesting, you could combine the two. The bowling team could choose one block of 5 overs between 11 and 25, and before the batting team begins their innings, they could nominate a block of 5 overs between 26 and 50. Don't tell me that wouldn't be interesting.