From the official website:
Lord of Ultima is an online strategy game where you build your own unique city and play with thousands of other players. Join now and rule a mighty empire which you can access from wherever and whenever you want.
All you need to enter is a normal web browser...
Reception from long-standing Ultima fans seems to be quite poor, as can be seen from the articles above, and discussions below:
Note that screenshots are hard to come by because people participating in the closed beta are not allowed to distribute any.