If Nostalrius can indeed provide the high quality scripting (looking especially at questing 1-60 which is usually quite unpolished on other servers) they promise & the server is stable during the first week then I am sold.
But that is just me, maybe your priorities lie elsewhere
But from my experience a (MMO) Let's Play needs 3 things:
#1 An entertaining personality
#2 Server Stability
#3 Interaction with other players
#1 can't be provided by any server
/ #2 will be tested during the first days/week / #3 will be available during the first weeks if #2 is given (making any guesses on future server population is futile at this point in time)