Tamriel Unlimited is the move to a new payment model. ESO has adopted a buy-to-play (B2P) model for players. With ESO's B2P model, you get the full ESO experience with no restrictions. No limit on what content you can do, no nerf to xp gains or gold caps. You play the full game. The only thing you would ever have to pay for is future DLCs.
There is still a subscriber option called "ESO Plus". As an ESO Plus member, you get 1500 crowns each month, a 10% boost to xp, gold, trait research, and inspiration and all DLC for free. If you drop your membership however, you lose access to the DLC unless you purchase it.
"Crowns" are a new currency added to ESO. Crowns are currency used to purchase items through ESOs in-game store, The Crown Store. In this store you can purchase cosmetic and convenience items. Items such as mounts, pets, costumes, potions, soul gems, etc. Potions are better than what you can find from merchants but not as good as what can be made with alchemy. The only way to get crowns are to purchase them from The Elder Scrolls website, or get some free as an ESO Plus Member.
One of the newest additions to the game has been the first part of the Justice system. Now you can be the thieving murderer you've always wanted to be. Break into peoles homes, steal their lewts, pickpocket them, or simple eliminate them all together. Be warned though, get caught and the guards will exact justice upon you. Depending on your crime, they will either catch you, forcing you to give up all your stolen goods and pay a fine. Or kill you on site. If you can get away unnoticed, you can go to a refuge to fence or launder your stolen goods. Stolen goods can only be sold to these people. And if you have a stolen good that you want to give to another player, you have to launder it first. Removing the "stolen" tag from it. A new skill tree "Legerdemain" has been added with skills to improve your thieving ways.
Another of the new things added with Tamriel Unlimited is the new "Champion System". The Champion System is a replacement to the previous Veteran Rank system. At lvl 50, you now earn Champion points as you gain xp than can be used to improve a number of passive stats in a way not so different from skyrims skill trees.
These are just a few of the changes to the game not to mention the numerous class balancing and tweaking done. Now is the perfect time to give the game a try or even a second look if you've played it before.
ESO Supports ADDONS!
ESO has addon support for most of the User Interface. You can get addons from a number of places. I suggest getting them from ESOUI.com or you can get some from Curse. I've noticed that ESOUI tends to have more up to date. And if you do use ESOUI I can't recommend enough for you to use Minion! It really makes adding and updating addons for ESO a breeze. And it has a nice, clean interface with little to no disctractions.
DISCLAIMER: This is a thread about ESO and ESO only. Please guys, no game bashing. Try to keep on topic and be kind to others.