Guild Wars and World of Warcraft are very similar to each other because it was the creators of Guild Wars who created the basis of WoW a long time ago, though much has changed due to VU's hand in the development process which advertantly caused them to leave and form their own company, from what I understand.
The combat is 100% similar, but the way you attain skills in World of Warcraft is very, very drab: you go to a trainer and pay him some gold for skills. Most of the skills aren't even very useful. The recent (few months ago) implementation of "Talents" in World of Warcraft was supposed to create a lot of variety for characters by adding a lot of utility spells, but a lot of those spells have been since made necessary for classes to take. Previously, a player could go about without talents and play well. Talents were a plus. Now, talents are a necessity, and half of them are useless. If there is a good talent, people will whine about it and they will make it useless instead of making the useless talents useful. It's a repeat of Everquest all over again.
World of Warcraft used to be fast and fluid especially in the early levels, but monsters have since been beefed up and players gimped. While it was previously possible to gain talents at level 1, you now have to wait until level 10 to gain talents. Skills have been removed from the game and replaced with limited professions, of which your character can only have two, in order to 'balance the economy'. Some professions are a waste, like Alchemy. The only time you'd use alchemy would be to give you a small advantage in PVP, but PVP consists of nothing more than zerg rushing. There's nothing tactical about it: It's all about numbers, and the larger group with the higher level players will always win.
Instances are mind numbingly boring, not because of their mission-based set up, but because monsters within instances are all classified as Elites. They're 4 times harder to kill and 4 times stronger than the average monster of that level. It'll take a few characters just to take down a single enemy, so the game plays at a snail's pace. What's worse is how those monsters respawn after 15 minutes, meaning you'll have to push on. If anyone dies there isn't a priest in the party, the instance is pretty much over, regardless of how deep you went in. Guild Wars suffers from a slightly similar problem - but that only pops up if a few members of the party decide to leave completely. Death won't hurt a party too much, as everybody has the capability to resurrect in Guild Wars.
Gameplay in general has also been slowed down, as it's impossible to kill a monster more than 2 levels higher than your character. It's possible to solo monsters the same level as your character, but you will have to rest for a minute in-between monsters and if you face more than one at a time, you're screwed.
Unlike Guild Wars, crafting is useless. You'll have better luck buying something you want from an auction or finding it yourself, or getting it as a quest reward. Spending any effort in crafting is a waste of time because the equipment is sub-par. The only people who would devote a lot of time to it would be people willing to mine for hours and pursue all of the stupid crafting-related quests just to 'skill up', as it were until they are capable of crafting one of the more useful recipes, like Mithril Spurs (which increase mount speed), Shield Spikes (useless now), or one of the better Thorium and Black Iron equipment from the high end insstance. It's an 'ubergamer' thing. Casual gamers shouldn't expect to see any of that equipment in their entire gaming lifetime.
