I've done both types of servers, PvP and PvE. My first warrior ever was on PvE and he is at 70 and kind of forgotten. Now my new warrior and druid and shaman are on PvP and I have no plans of ever going back to a PvE server.
I will actually go to STV on the weekends with my Shaman because it is fun for me. I like getting into it with Alliance and starting the small scale wars.
I will go and park my 70s in STV, play my 35 Shaman. If the ganks are by the same level toons then we just fight and a have a good ole time. If the 70s show up and kill me more than once, I log Herk or Aerthson and we get into it and a good ole time is had by all.
The other part for a PvP server is questing and gathering. You can actually kill that tard who tries to gank that node off of you. Sure they could be your faction but this happens rarely with Horde in my experience.
Questing also becomes competitive and more interesting for me. In Ashenvale if you are Horde on a weekend, it is well advised to stay OFF the road and to duck out of Splintertree as soon as you hit the landing on Flight Path since a 70 hunter can sit there and one shot everyone who lands without aggroing the guards. There are all sorts of things that add up to make my experience in WoW altogether different than on a PvE server. On PvE, you do NOT have to get off the road unless you want to. On PvP, going through “the wild” is almost a must given the area.
When Wrath opens up it will be balls to the wall action in trying to get that quest done before the other 70 faction shows up. No one will know the wilds and there will be roaming bands of factions trying to stay safe out there.
I have a history professor who said that if anyone had seen the movie Jeremiah Johnson about trappers back in the day, to disregard it completely. Trappers back in the ole days where roaming, well-armed and defensive gangs rather than one lone man. The same can be said for WoW on PvP. If you are questing alone and don’t want to be bothered, you need to roll PvE. On the other hand, if you like to quest with a bit of danger other than mobs and your own stupidity (I can not believe I walked off of Tanaris into Un’Goro that one time0 then you should try PvP.
On the Isle of Quel’Danas right now it is not unusual to see the gank squads of Alliance form and delcare war on any Horde on the isle which leads to Horde declaring war and it is go time. Full on war at it’s best.
It's PvP server guys. You either like it or you don't. Sometime it's the moral victory that counts. When I was bringing Herk to Badlands through Loch Modan, a 70 Dwarf Rogue made it his mission in life to kill me and get me to log before I made it to the Badlands. Knowing what I have gotten myself into, I kept rezzing and walking. We gathered a LARGE crowd of Alliance who would keep killing me after I rezzed. I would make it a ways a away from my actual corpse because I would rez at the very limit and keep on walking. Sure it took a long time, but that Dwarf left me alone before I logged. Moral Victory or just sheer stubbornness? I leave you to make up your mind.