With out a doubt it is... ask any person who has been in beta for months. They will tell you the same thing.
If you go and just kill mobs for lets say 200exp a pop, you will 20 in the spand of 25 minutes. You now have 4000 exp.
If I pick up a quest to obtain 10 quest items, and it takes me 20 kills. I now have 4000 exp, and a quest to turn in for a average of 1500k exp on normal quests in mid 20's. Small exceptions being you may have to travel a extra 5 minutes to get to the spawn point.
You can also share the quest to do it twice as fast (I did that last night with a guy, and we banged out what would of been 2 pain in the butt quests) Yes you get half exp on mob kills... so thats 2000exp, and you still get your 1700exp for the quest, a little less exp, but twice as fast!! I did two quests last night quicker than it would of took me to do 1. Which in the sum of things, is still more exp, and less risk.
Also... I know their is a lot of crap on the beta boards, but I know for a fact people grief. On the PvP server many times higher levels will roam crossroads or brill and killing lower levels as they spawn. Also, I believe their is a few videos on www.wowvideos.com that show a whole raid party camping corpses. I consider both of those griefing
I'm not trying to discourge you guys from going PvP, but just be prepared for this crap, because as good as Blizzard will be, their GM's will not be able to controll it all during the day, and they wont be around late at night.