I can certainly see both sides of that discussion. One hand, a unique experience with even more nostalgic stages/bosses than we would have had with the consoles alone is awesome. On the other, a scaled-down version (obviously the 3DS cannot handle a direct port) that included some actual 3D stages would have been appreciated as well. I'm happy with what we're getting, but I can see why some wouldn't be.
I got some hands-on time with the 3DS game today, modern Sonic in Mushroom Hill Act 2. The game moves extremely quickly, and the screen is panned back fairly far, which can at times make things difficult to see. Thankfully, the over-use of bottomless pits is gone, and loose rings are pretty easy to re-aquire, so the game wasn't necessarily frustrating. It might take some getting used to. I'd imagine that classic Sonic, being without the boost and all, is a little more user-friendly. But IIRC his stages in the 3DS are fairly straight ports. I didn't get to confirm this for myself, though.
Also on DeviantArt, Rumble, DLive.tv, and the Fediverse (@freespeechextremist.com and @bae.st)