Guildwars seemed to be a PvP oriented game with an introdutory PvE content, but since then it has changed considerably.
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1) One of the good things of Guildwars is that unlike many other MMORPG, you can actually play a variety of characters with very different playstyles, without losing anything in the competitive side. Its just great to be playing a frontline character and then just shifting to a monk and having completly different roles.
The bad of it, is that Guildwars has 3 campgains with loads of un-interesting quests or missions, or at least boring and annoying once you completed the same 3 campgains with a few characters. Then leveling up and acquiring the elite skills and the locations of the true high-end stuff is completly boring.
In short, while its amazing to be able to field 10 different professions, is ridiculously annoying to have to complete 3 different chapters, wich are mostly low to mid-level difficulty.
Hope for GW2: Being able to field lots of different playstyles, but actually being able to employ them in really hard areas, where you need teamwork, isntead of just dull missions, that you can complete with your party of henchmans. Theres few feelings that can compare to being able to field a team of guildies and just mop FoW, DoA or any of the new dungeons.
2) Heroes- Some people complain about heroes, saying that they kill player interaction and that its impossible to find parties. There is some true in that.
On the other hand, being able to play solo, either because you like or because noone of you friends are online is great. Being able to avoid people that dont have a clue to what they are doing and still dont follow is great. Ofcourse sometime you will just miss that guy/girl thats a good player and person.
Additionaly, being able to finish the game with just a friend and both our heroes is amazing.
In short heroes have pros and cons, but in my opinion, the pros really outweight the cons. Hope I will still have the choice to play solo or with 1/2 friends in GW2.
3)PvE vs PvP- Apperently theres some kind of edge between PvP and PvE players, and I cant say that I dont get annoyed when something thats ok in PvE gets changed because of PvP (mostly GvG and HoH). But I m also a PvP player, not a serious one, but I know that from time to time I like to go and face some human opposition.
Hopefully in GW2, PvP is kept, but the skills used in PvE and PvP will be split.
4) Grinding- A very nice thing about GW is that no Grinding or very few was necessary. But that seems to be changing.
Sure, players need stuff to do, to stay interested and have long term goals, but I think that should be done differently.
Make high-end PvE content challanging and more rewarding. Make titles and stuff, that can be get by exclusive play of High-End content, and not by going and kill that same poor mob over and over again (and I'm a farmer

Chests in High-End areas was the perfect move. Just make those areas tough enoug and rewarding enough, that doesnt get boring doing them over and over. But an eye needs to be kept for those that dont have an established guild.
Hope for GW2- More areas like Urgoz, Dungeons and such, and not "I NEED TO KILL MORE 10000000000 enemies so I get lvl 99 or get that title that will make me pwn!"
5) Items- I like that what makes high-end armor and weapons differents are the look and not the stats. On the other hand I dislike that those supposed "rare" (all that show in gold letters, not that rare skin) items in the game, are mostly crap with +17% damage while under 50% health ("DONT HEAL ME STUPID MONK, I WANT TO DO MORE DAMAGE", right nice idea) and not true good weapons. I would rather make them scarcier but all good and not "YAAY, another gold item for the merchant

I hope GW2 keeps a similar item structure, and dont goes into a Diablo 2 fest (although killing Mephisto 100 times per day was fun
6) Script or not Script- Being a private world once you are outside, means that it looks less of an open world, but it makes you avoid annoying things like higher lvl players predating lower lvls, or the need to wait for something to respawn. Also missions and quests can be more interesting.
It depends on how it will be implemented.
7) Chat system and guild/alliance identification- Ok this thing is attrocious. And please, please make possible to have a master name, lets call it, so you are always named the same, even if your characters have different names.
Also not being able to see alliance rooster is just damn annoying.
Lets not talk about trading chat.
Chat system really needs some work,
8) To conclude, I like the way GW is about options and not about tireless and mindless grinding. Sure some type of grinding with some decent rewards, like the treasure hunter or the wisdom titles, for example, are fine, but making them mandatory doesnt saound good.
For Guildwars 2 I want still be able to have different options, but more High-End stuff and less "newb islands" and lots of uninteresting and easy missions and quests.