I've played em all and Tabula Rasa brings something fresh and new to the game - fun without the grind.
This has been my experience with MMO's up until Tabula Rasa. I played the Beta and yes it was buggy as hell but what Beta isn't? I started over at release and thogh I was bummed to have lost all the work I put into my Beta character, I never felt punished to have to do it over again.
Every zone in TR is better than the previous, the instances are more complex and the story is well weaved. You can log in for an hour or for twelve and enjoy yourself either way.
I just wish they would do a 14 day trial period so the lurkers can actually give it a shot with little to loose, the player base would triple overnight.