I consider myself a booster of 4E D&D. I do have some issues with it though. I consider spell-casters a bit limited, especially with the lack of decent divinations and charms. I can get a little frustrated with its dependence on miniatures (even though I love painting them). Most of all, I am disappointed with the multiclass rules.
Part of the problem is that I was a big fan of the multiclass rules in 3E D&D. 3E multiclass had a certain elegance that was lacking in what had come before and what has come since. It is true that there were some issues (e.g., caster level and dipping), but I felt the good far outweighed the bad.
On the other hand, the 4E multiclass rules have a tacked on feel. Which is not surprising, because they were! When 4E was first designed, they made a conscious decision to prioritize single class play, and not to worry about things like dipping. The multiclass rules were only pursued later, with an eye towards preventing the abuses common in 3E D&D. Unfortunately, the end result left you with a character who was mostly one class with a mere sprinkling of abilities from another. A far cry from either the layered multiclass characters of 3E or the versatile fighter/magic-users of old.
Hybrid characters, introduced in this month’s Dragon, are an obvious attempt to fix the problems with the multiclass rules in 4E. In practice they seem very similar to the 3E gestalt character rules introduced in Unearthed Arcana. The big difference is that the in 4E rules, where all classes are built around class features and powers, this actually makes a lot more sense.
Hybrid characters are an excellent solution on how to create multiclass characters in the 4E rules. While they lack the versatility of 3E multiclass characters, the hybrid rules create characters that are very reminiscent of those created using the 2E and 1E multiclass rules.
In my mind this is a vast improvement over the current multiclass rules for 4E. Not perfect, but definitely functional. Now if only they can make some decent charm spells!