That thing is just jerky. Double jumping in Colors felt smooth and intuitive. Sad to see it go.
I don't really mind the airdash, so long as it's just that and not boosting in the air, although that is a fear.
I personally felt the entire reason double jumping was included was because the controls of Sonic Colours were worse than that of Sonic Unleashed. When playing certain acts in Planet Wisp or Starlight Carnival (?), if the double jump was not there, would have lead to much more deaths, and even with it's inclusion the controls still aren't as good as Sonic Unleashed (Which in itself had some control issues) and lead to some fairly cheap deaths.
I don't really get what you mean with sonic feeling exactly. Sonic colors showed lots of more similarities to the classics then the boostfest from sonic unleashed.
I actually dont feel Sonic Colours shows much similarities with it's level structure or feel to the classics as opposed to more similarities with stuff like Kirby, Mario etc, as I said, that is not a bad thing, since those are good games, but to me the level design does not feel much like Sonic at all.
Of course, Sonic Unleashed does not either, though I feel the fast paced nature in more inclined with the series, but at the end of the day if I had to pick which Sonic gameplay was going to pick to fill the other 50%, I would go with Sonic Unleashed, I just found it much more enjoyable than Sonic Colours which I've yet to complete despite having it for several months. As I said, does not mean it's a bad game, but I really did not enjoy the title much at all. Nor am I someone who wanted the boosts in the games (Or funky powers) but 50% of the game is going to be classic Sonic and so far so good.
My only worry is some of the stuff they put in Colours (Such as lower platforms to fall onto) are going to be completely forgotten, but thankfully the grindrail sequence we saw had lower levels of grindrails, I hope their forgiving streak continues.
And at the end of the day, Sonic Unleashed gameplay is needed for the most climatic battle in the series' history, the race against Metal!
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Only a totally seperate note, Ruby made a few posts at NeoGAF that I see have not been posted so I'll post them here;
Stay tuned, though - there's some good stuff to come as we reveal which games and zones we picked from for the three main eras. (Genesis, Dreamcast, Modern.)
Also, I just tested the rolling off ledges bit as mentioned above, and many of you will be happy to hear that you remain in a ball form. And yes, you can also use the classic "hold down+jump" method to rev up your spin-dash. 
Classic Sonic has his own set of distinct physics, which are closer to the classics than anything since - including Sonic 4: Ep1. It's not based on Colors.
Keep in mind it's Ruby and it's his job to sell the game, but I suppose there are stuff some people would be interested in knowing.
