What to expect:
Currently, there is a free version of Ultima online with the release of Endless Journey. When choosing a server if you are in America the most populated server is Atlantic, however, with the recent increase in players, some of the others are becoming active again like Catskills, great lakes, etc. Skills can be trained very quickly and getting the needed starter items is as simple as asking someone in general chat to "hook it up".
If you are wondering ok but what kind of character do I make. There are a ton of combinations but there are also items in the game called soulstone and soulstone fragments that allow you to store your skills and swap them in and out so don't be too worried about your template when starting out.
Mages: Magery, Necromancy, Mysticism, and Spellweaving are all mage caster skills some require other skills to do damage such as evaluating intelligence for Magery, and spirit speak for necromancy.
Tank/Melee: Warriors also referred to as "Dexers" and Sampires are based on which buffs and skills you combine with your melee fighting skill. The Melee fighting skills are Maces, Fencing and Swordsmanship. Parrying is used with a shield or a 2 handed weapon to block attacks and make hitting you more difficult.
Ranged: Ranged fighters that use weapons consist of archers and a new skill throwing. Throwers need to be of gargoyle race in order to equip weapons. These type of characters are great for dps and pvp.
Crafter: There are a ton of skills related to different crafting methods in ultima online. So much so that most people build a character with just 80 magery and the rest goes into all crafting skills. This allows you to have 1 character who can make everything.
Tamer: This is a very important character to have if you are into the pvm side of things and like to do end game content. With a tamer you can customize the builds of your pets to be dps, tank or even AOE. There is also a new very strong pet out called a triton which requires high seas expansion to accept.
Thief: That's right you can become a dirty little pickpocket or become a dungeon scavenger stealing your way to riches. In UO you can have a skill called hiding and stealthing which allows you to walk around invisable. Snooping skill allows you to peak inside peoples bags for things to take using the Stealing skill.
The change to houses:
Houses are still a very big thing in UO and on atlantic there is really no room left to place anything. A new change has allowed people to upgrade things like keeps and castles and turn them into customizable plots. Houses still decay after a player quits game and eventually falls with all of the loot on ground.
Resources: https://www.uoking.com/, https://www.uoking.com/UO/Gold