My thoughs are: Vasj'ir is an interesting zone, sadly, it annoys me and bores me after a while. You can only view a certain distance, it all looks pretty much the same. Generally I don't like dark zones. Mount Hyjal was good, Uldum was good, and Deephold + Twilight Hyjals were ok.
Some would say Wild Mushrooms are like landmines. I see them as atomic bombs on a ten second cooldown.
No.
For two reasons: One, overall the combat in 3D space was disorienting. Two, the quality of Vashj'ir questing dropped off after you boarded The Verne.
A Farewell to Pre-Cataclysm Azeroth (video)
Youtube: http://www.youtube.com/watch?v=fdlhcVG2p7M
WCM: http://www.warcraftmovies.com/movieview.php?id=168677
I think that due to a combination of the annoying/long/sometimes buggy intro quests deterred a lot of people and made it frustrating or just easier to do Hyjal, where basically you get a teleport there and the click on the dragon to fly, where in vashj'ir you have to wait for that damn boat to show up.
Also the set up of Vashj'ir was fairly confusing, with the three mini zones, and travelling between them being fairly confusing.
Overall though, I think the idea was great, the zone was beautiful, and having the linear progression of helping out the few main characters helped to make it appealing. IMO the biggest problem that blizz made was that you don't have to visit every zone to get to 85, since there were so few zones (only 5). I know in past expacs you don't need to visit everyone either, but when you had 7 places to go in WOTLK, I felt like they varied much more, since you were going to go to at least 4 of them. Leveling in Cata is too fast overall imo. Oh well. Hope they continue to make these awesome zones, just make them less confusing/less barriers to entry (that annoying ass quest to defend the boat that bugs half the time, or you just die over and over).