The first 20 levels are definitely like an extended tutorial which has been mentioned.  Combat early on is pretty slow because most of your abilities are locked into the global cooldown so you have very little to mix up.  As I've leveled though I've been picking up a decent amount of skills off of the global so the rotation if you want to call it that has gotten more fun to play.  I also have to assume as your get more skill or spell speed things will get a fair bit better, but I haven't gotten to the point where I have enough to judge yet.

It might just be me, but quests are rarely fun in most games.  They just always feel like tedious running back and forth.  Didn't really like them in WoW, here, or anything else.  Luckily here if you really hate them there are at least FATEs available that there are usually a lot of parties for.  I've personally gotten to the point where I only really do quests for my job or the main quest and just join up for FATEs to level.  Dungeons do actually get more difficult, the early ones are just extremely easy.

As for having to grind out other jobs, I can understand that.  They do actually give you an exp boost when you play a lower job until you get it to or close to the level of the one you've leveled highest.  Any secondary I've worked on hasn't taken more than maybe 2 hours to hit the 15-20 range.  You run into some more hostile mobs later as well, but it never really seems to get to the point in some zones in WoW where you'd get trashed just running through.

I would say try out a couple other classes during your 30 days and see if maybe the one you chose just wasn't your thing.  If it doesn't work out, at least it wasn't the usual $60 to buy the game.