I'm actually extremely excited about the new drummer. Don't get me wrong, I loved Portnoy and what he brought to the band, his drum parts just seemed to fit so well. Now, I'm sure this has been mentioned countless times by other people on the forum, but I'm really pumped to see DT without Portnoy being the controlling overlord.
I hope the change in drummer brings them more proggy sections and less rap sections. I mean, they kind of grew on me, but the first time I listened to Prophets of War and ANtR, those sections alone ruined the entire song for me.