I think i'm 15 hours in now, my characters are lvl 8, i explored most of the map, but I still have TONS of quests open. This alpha has easily 30-40 hours in it for me.

The funny thing about the starting class is that it only decides which spells you start with. All my mages became dex mages with spears :P, as far as I know intelligence gives more AP/lvl, it just works great to get multiple spear attacks off, or freeze someone and then finish him with a spear. You can for example choose a wizard and spec him as warrior and there will be no difference, only that you will have a heal and a flare. Especially when you go without a wizard it's nice to have someone that can heal. I really love this, as far I know there is no game like this.
A lot of those quests are like I met this guy and then nothing. But I guess it will trigger at some point yes?