Disney was getting so many people asking for arusha that they decided that they could charge extra - good idea. We stayed overlooking another savannah - forgot the name. Arusha is the one in the middle but they all are great. They have different animals. Sometimes the animals will get new homes, or new animals brought in. The animal staff at the hotel are awesome.
The only thing I would say bad about the savannahs are that they bring in all the animals off them to clean them up, and also to get the animals used to being inside (hurricane preparations). The schedule may change so I won't say what I think they are, but do be warned that there are times that the animals can't be seen. But they'll be there all night.