Playing with Udyr and Olaf so far, going to try the rest of my junglers out. Honestly though I feel as if Jungle is viable, it seems like most of the people crying about the new jungle are laners that have gotten stuck in a 2v1 lane and can't handle it.
It's nice be able to jungle and actually gank instead of oh they have a ward on elder...guess I cant go there, and man I really have to run all the way to top and be so far away just to level? This new jungle is epic...I expect to see more junglers and lanes turning into 1v1 with jungle support very soon, as soon as all the whiners stop trying to treat this like the old map and adapt and overcome.
The big problem right now is that people don't understand the map and altars, and certain characters do have an advantage. I.e. Teemo putting shrooms on Vilemaw, or in your altar which really serves no purpose but to annoy you.