I'm very fond of the system. It could go farther, but it really does have a lot more potential than people give it credit for. In my experience, trying to reproduce a 3E multi-class guy you had is a bad idea - instead, look for the new possibilities.
I even think the "total" 4E multi-class works out in some cases. A rogue with Eyebite as an at-will has a heck of a trick up his sleeve, as does a fighter with Radiant Smite. Is that better than +1 to hit and +4 to damage from kensai? depends how high level you are and how much you want to smack the undead around. The +4 is static, but undead vulnerability to radiant seems to just keep increasing. I do think being freed from the 3 forced paragon powers can be a bit of a blessing as well - almost no path has 3 powers I really want.
I'd like to be able to take some of the multi-class feats more than once, I'd like access to some of the unavailable class features, and I'd like some more paragon paths that work well with other classes. All might come in time.