I got about 4 hours of PvE time in while I was out at ZeniMax and I can tell you that if you like PvE you'll love this game. One of the coolest concepts i've seen in a game is the way that the PvE zones change based on the player in the world. It might get really confusing depending on how it all works out but I thought it was neat that it was dark, gloomy, raining and dead folk were wandering around this cave. I had to fight my way into the cave and slay a necromancer. After I killed him I exited the cave and it was sunny and the undead were once again dead on the ground. There was even some NPC's lurking wondering what happened. Now I ran across another fellow who just happened to be sitting right next to me. He hadn't slayed the necromancer yet. On his screen it was dark, gloomy, and undead were wandering around. ON my screen it was bright sunny and the dead were dead. Now when I joined his party the dead became undead, the clouds came out and it began to rain. I went in and killed the necromancer again. Then both of us saw it sunny.
I also go the chance to explore one instanced dungeon and one open dungeon. The instanced dungeon was all story based kinda like Guild Wars 2 dungeons. The Open Dungeons were like mini-zones. The further out from the start point you got the tougher the enemies. We formed up a 10 man group to see how far we could get in and killed some bosses but in the end there was no way we were getting through the deepest areas. Not even close. The deeper you go the more people you need to complete it. The enemies work together against you. They flank you, they decoy you, they will run in front of their wounded to shield them from incoming attacks while they heal. They will give each other abilities by combining attacks.
Combat wise it was slower than GW2 but not like RIFT. I'd say it was somewhere in between. You don't have cooldowns but you do have stamina. Each time you block an attack you have the chance to counter it. You can retaliate with a heavy attack. However blocking an attack takes a bit of stamina. Overall I had quite a bit of fun with the PvE world. What I can tell you is that if your tasked to save 9 npcs.... go save 9 npcs. I just said screw that and went on without. I got to the end of the area and I had to stand off against an army. If I would have saved those 9 people there would be 10 of us facing off with this foe (about 30 npcs). However my adhd butt decided to go without and had to go 1 on 30. Every little detail will change the future of you experience. This is the closest thing to having a single player game embeded into a multiplayer game seamlessly. It really innovates the whole "Personal Story" idea.