Its the wow of 2006, so no expansions just vanilla wow, BUT all of the major boss fights in raids are custom scripted to be more interesting so its potentially even better.
The only problem is that vanilla wow required your entire life because there are 40 man raids which pretty much always happen late into the night on friday and saturdays.
TLDR if you ever wanted to try wow when it was hard and not for casuals, this is as hardcore as an MMO gets but its also going to consume your soul.