Actually, Ebonyks, I do think his two major weaknesses have been adressed in brawl. I'll give my explanation, and if you think I'm missing something, just let me know.
The major weakness of yoshi in melee was no jumping out of shield, most pro players will agree with that. Because of L-cancelling, shield grabbing was for the most part not an option, due to yoshi's slow grab and less range than he should have had with it. In brawl, there is no more l-cancelling, so apart from the special few that have no landing lag now, most aerials leave the opponent wide open to be shield grabbed. After playing the past few days, I think yoshi's grab has a bit more range than it used to, so shield grabbing is a much better option for yoshi now than it was previously, and for the most part solves his lack of jumping out of shield. I'm sure my arguement has its flaws, however, so feel free to argue my point.
The other problem was yoshi's lack of a third jump. This has obviously been solved by yoshi's ability to not only gain vertical and horizontal distance with his egg throw, but do it multiple times. I've found that after four egg throws, he doesn't get any more benefit from it, but that's a lot of distance right there, and combined with it being a projectile this is a very effective recovery. It also makes ECE's a lot easier, as I've stated in another thread.
For now at least, I'll agree with you on the DJC issue. We really don't know what can truly be done with the full double jump, so we can't just go off and say that it's great. I'm sure there will be useful combos for it, but only time will tell.
And on another note, guys please don't make this a heated arguement or a flamewar. That includes everybody from both sides of the debate. Next time you wanna blow a fuse here, just think to yourself, what would yoshi do? =P