I spent a while in the practice tool messing with him and the only thing the rework seems to offer is more healing from Q and a faster way back to lane with W. The passive felt like a poor man's blood boil and it lasts such a short duration that in a 1v1 or 2v2 situation you wouldn't even feel it. The Q is decent with 50% ap scaling and the healing from minions is massive and a cooldown that actually scales down unlike the new w and e. W has decent damage at max range but otherwise feels worthless while anywhere near champs unless used to chase people down but a 13 second cooldown that doesn't go down and a knockup that's shorter than Viegar makes it just _ok_. E is just disappointing with a 5% ap scaling, almost no slow if any and the root that requires you to stay and range with someone despite nothing but w to keep you on them with a static 13 second cooldown not to mention you have to wait out the whole duration for the snowbound thing to pop and even with 800 ap feels like a sad joke for damage compared to the good 'ol snow ball that had a 90% scaling and a 60% slow and a cooldown that went down to 4 seconds. The ult is basically the same though they just added a shield onto it. The only thing I can really give it is that with 800 ap and 45% cdr you can solo baron with nothing but the Q due to the healing.
I'd like to see other's opinions on this since I might be biased due to really enjoying fooling around with old full ap nunu.