Buggy as hell with tons of exploits, but pretty entertaining and awe inspiring for a day or two none the less.
Elder Scrolls Online sounds like it could be the first truly successful sandbox mmo since UO because it's got the financial backing the developer talent and a decade worth of franchise history behind it something no other sandbox mmo has really had other then UO itself.
You might say Star Wars Galaxy, but I don't think it really had enough of a dedicated financial backing and developer talent behind it and gutted prematurely by Sony to cut back and distribute else where within the company.
The difference between them is Elder Scrolls doesn't have a side project it's make or break, but it's got the financial backing and developer talent and every successful mmo has had those things in common.
WoW, EQ, UO, Lineage, and DAOC were successful because they had the needed finances to make a quality product for it's time and had the dedication and talent to do so as well.