This review is from a seasoned vet after all stand alone games and the expansion have been out.
When you purchase a game like Guild Wars the review from when it first came out and the reviews 5 years later are completely different because the game changes so much. I've been through it all, having played since its beginning. I was a truly avid fan of the game and I still am, but something is different now than it was before.
Problem one that detracts from the game is that there is just too much. I don't mean campaigns or multiplayer options I mean there is too much customization. It has reached a saturation point where now it's impossible to keep up with all the different skills, combinations, strategies and tactics that used to separate good players and bad players. When core (Prophecies) first came out, there were 6 classes with 150 skills each. Total that's about 900 skills and you could combine these skills in thousands of ways. But a good player could manage this. Now it's impossible. There are too many skills and too many classes and too many strategies and it's impossible to keep up with everything.
Now you often see a few things happening - instead of skill being the determining factor in who wins a match it is often by sheer luck that someone wins. Or someone will copy one of the OP builds they found online and just use that constantly - ie necro bomber which is used constantly to cap in multiplayer modes - this build ruins the balance of a match and is overused by those without skill in order to achieve a quick win, which ruins the basic premise behind the game which is that skill should be the determining factor in victory. This particular build has been active for over a year now, and A-Net doesn't seem interested in patching it.
The other issue is the hero henchmen. It seems like a great idea right? Fully customizable team of henchmen you can take with you where ever you go. It's a terrible idea. Here's what it did: when guild wars first came out you would party up with a group of 6-8 players, maybe bringing a monk henchman if you needed it, and you would all go crazy in a mission and kick ass and either argue or tell jokes or whatever. Hero henchmen ruined that, it caused a disconnect between players. Now there are two people max in a group each one bringing three henchmen, completely destroying one of the other core principles Guild Wars was build upon - teamwork to achieve an objective.
The other thing that ruined the teamwork principle was an overabundance of standalone games. Guild Wars needs a certain level of saturation in order for people to queue up and play through a mission together. What are you to do if there are 4 games out all connected and there are two people looking for a group to play the mission you're in because it's not the newest game out? That was a big fail.
Essentially the two things that Arena Net used to make Guild Wars into a great and fantastic game at the start have been eroded. It is for this reason I will give this game a 5.5 even though I'm still an avid fan of the series. I love the game for what it used to be, but never again will I be able to jump into a mission with 7 strangers and feel the achievement and elation of rocking the hell out of it because we just synced well together. Never again will it matter how much preparation I spend in putting together a build for pvp because there is no way to compensate for every play style anymore - essentially you're going to lose consistently to the pop builds. I think I'm most sad about the erosion of the necessity of teamwork, but I really hope that Guild Wars 2 brings some of that back.
If you're new to the game, don't jump in. Wait for GW2 and play a different MMO til then.