Ben looks the same as he did in UAF, and it is confirmed that he will eventually look the same as he does in Omniverse.
When Ben was 10, he received the Omnitrix, not knowing what it was. As time went by, he became more and more skilled at using his device. He found out that it was created by Azmuth. Ben eventually took the Omnitrix off, but put it back on when he was 15. He had more adventures. When he defeated Omeub, Azmuth rewarded Ben with the Ultimotrix, which had Ultimate Forms and new aliens Ben had never seen before.
In the series Evan Billion, the main goal of the protagonist Evan Levin is to locate Ben. However, Evan has several doubts that Ben is even real. Kevin is Evan's cousin, and his #1 objective is to keep up Evan's belief and locate Ben.