Sacred is almost excellent. There's a lot of fun to be had in exploring the wide world and killing heaps of monsters, but there's one significant flaw if you ask me: the item system tries to be "better than Diablo 2", but it's not very thorougly polished.
There's too much clutter and useless items in drops, and another problem is that you may get 10 different kinds of bonuses in one item, but they may all be very diminutive in power. Some bonuses (and skills) have very unclear descriptions, and you have to guess if some things stack or not, etc. Makes comparing stuff hard. There are way too many magic item properties that are obscure and very useless - like "2% of Dexterity Dealt as Fire Damage Against Skeletons" and all possible variations...I realize that people want to try and make different kinds of character builds, but these types of ridiculously marginal bonuses are just too much micromanaging.
Also, the dropped items have names that should vary logically according to their attributes like in Diablo 2, but they don't. They are just random, and there are very few variations (there was even some axe that was named "Sword of..." something...) Doesn't break the game, but feels very cheap. Overall the game is haunted with a fair amount of cheesyness.
If you can set these things aside however, and not compare too much to Diablo 2, Sacred is quite a bit of fun. The character classes are diverse enough (and the Seraphim has high heels ;D), the combat is fun to play most of the time, and especially with a friend online, one can get drawn in for a long time with this game. There are so many side quests in this game that you surely won't run out of things to do. Aside from the item system, the technical production brings Sacred past average level.