Do I want to buy this game and is it an online game????????

It's not out yet, and it won't be for some time. And it's an online, but also a single-player game. Go to http://www.sorcerers.net/Games/NWN/index.htm and read all about it.

Thanks is it going to be like uo.

No, as I said, it's not an online-only game. And there will be no official servers with content to play the game on, just a character vault which will store legit characters.