Highly Overrated. It starts out fun, but quickly turns monotonous.
First of all, this RPG is horrible broke without some type of leveling mode. A RPG where you have to carefully pick your skills or else you will "level too fast"?? You have to pick skills you don't want just for balanced leveling?? What kind of stupid role-playing system is that? Second of all, the enemy mobs, dungeons, and gates are all too monotonous. Sure, there are a ton of them. But they are all carbon copies of one another. How many skeletons and scamps will I need to kill? How many gates of the exact same type with the exact same textures and exact same enemy mobs do I need to close in this game? Answer: too many.
Third, there definitely are a lot of quests in this game. The problem is that 80% of them are copy-and-paste versions of each other. I played through many quests, yet there are only 4-5 of them that are truly memoriable. The rest just felt like I was repeating the same motions.
Lastly, I consider the combat to be a bit on the boring side. The spells are generally lame, and combat options are severely limited. What you do at level 50 won't be much different than what you were doing at level 10. You will just be using "stronger" versions of the same stuff. But since your enemies will always be as strong as you (unless fixed by a mod), you will still be doing the same percentage damage as you were at earlier levels.
What this all leads to is 20 hours of great gameplay, followed by 80 hours of doing the exact same things over and over until you collapse of boredom. I suppose some people just don't mind the monotony, which is what explains why some people think this is the best game ever created.