I didn't play the first and second parts much, so I can't say much about them. The graphics are simple but cool (especially in the first one - there are no other games with such awesome thieves :cool:). And in the second one, the gameplay is more diverse - more towns, creature upgrades, hero progression, etc.
The third part is my favorite. :smile54: It's well-balanced, and the graphics are good, even though it's 2D. In general, it's a classic - once you start playing, you can't forget it.
A separate word about Warlords - it's a game for a change of pace, so you don't get bored with the classic third part. I agree that many scripts and abilities in Warlords are unbalanced, but that's the point - you can turn off any imbalance, and generally enable whatever comes to mind - complete freedom of action :smile13:
The fourth part is, in my opinion, the least successful. I'm not saying that this game is :smile18:, it has many good ideas that have been carried over to the fifth part and Warlords. But compared to the third and fifth parts, it doesn't look very good :( Maybe the pseudo-3D graphics are to blame, or maybe it's just too radical changes in the gameplay.
The fifth part is also a very good game, combining the best of the third and fourth parts. But sometimes the graphical enhancements distract from the game itself. And my computer is too weak for such graphics...