After seeing the trailers, not to put down previous Kirby titles, but I get the impression that this is the first Kirby game that really feels like a top-quality game. Now, I haven't played them all, I still need to put more time into Kirby Super Star and Dream Land 3, get the GBA ones, and I don't have a DS, but I've played a majority. On the whole, I've always thought that Kirby has had great gameplay ideas. Copying enemy abilities is a good concept, there is a lot of variety to that, and it's enjoyable to try them all out. But the stage designs have never risen up to that same level of ingenuity. Not that they've been bad, they certainly haven't, but they don't have the variety, and most stages aren't built around having abilities.
Kirby Epic Yarn feels like the first time where the stage design comes together with Kirby's abilities to create one unique and fun experience. It focuses on one or two abilities, so they can create stage designs around that, instead of having to compensate for a dozen abilities. I know this means the removal of a series staple, but sometimes that's how it goes. As much as I've enjoyed Kirby games, I've always seen the series as B-list, second-tier. Of course, part of that may have to do with how Kirby games tend to be late releases on a system, so they don't get much attention anyway.
Now, for those who don't like the change in focus, I doubt this game is going to set a new standard for Kirby. In fact, since this isn't what became of the Kirby GameCube game, for all we know, that one could still be developed. Nintendo have shown with series like Mario and Metroid that they don't mind releasing two different types of games in the same series on the same system, so who knows, we could see a more traditional-style Kirby game in the near future.