As people have said, Wardens are great fun, but you will have to work hard to be "accepted" over a guard for most Groups..not because the class sucks but people have no idea how to work with a warden in a fellowship/raid.
Common examples : Hunters burns too hot quickly, Minis panic and over heal you rather than trusting you know what are doing, or RK put down their stone right on top of where all the squishies are. Repeat after me ... Wardens build threat up over time, we have very few quick grab agro skills. And lastly yes it takes us 20 secs to get through our battle prep routine...deal with it.
Also when squishies get the agro they run around like headless chooks ..rather than running towards the Warden (or tank). so we can scoop up the mob with some EOBs or call to battles with out having to play tag.
Once your group gets used to having a warden as main tank, there is nothing you can not do.
"When I want your opinion, I'll read your entrails"
- Worf has Spoken!
Worfie - Warden