Dude, I know what you mean, I'm a huge fan of the series as well, the character "concepts" were pretty awesome in that you had everything for everyone, you had you summoner your strictly magic character, your knight fighting for justice, etc.
But, the imbalances and stupid decisions they made on the later patches made it a bad online game. But the mythos is rich and the single player (or multiplayer lan and such "non competitive games" was fun as hell.
You should really check out all the latest developments for the 3rd one, diablofans.com is a good site to keep up with the news.
And btw, on blizzcon a new class may be revealed. Should be awesome.