My first stay at AKL was on the Uzima savanna. I thought the location was great as we were close to the lobby, pool, and restaurants. We had animals outside our windows at all times.
On my second stay, I chose the Arusha savanna. It was the most requested view in doing all my research. We loved that view as well, especially the zebras sleeping outside our window.
Having done both savannas, I would not pay this new premium on the Arusha view. There are so many viewing platforms to look out on Arusha if you feel that you are missing out. I would prefer Arusha over Uzima, but I would not be willing to pay for it. But that is just my two cents.
Quick edit - I just realized that you said only Arusha was available. If your heart is set on having a Savanna view, I do not see where you have a choice but to pay the price difference, so not sure how much my post helps you out.