I skipped Gen 5 when it was out and the Global Link was active for it due to burnout, so the 3DS games were even more of a change from what I knew beforehand. The usual comments apply here—some framerate problems, very hand-holdy and lenient gameplay at times, and characters that don't leave too much of an impression. I'll argue that the series's had a forgettable character problem for a while, at least with the gym leaders—but it's true! The partners don't stick very much, and the team admins aside from Lysandre get as much screen time as a stick of butter in the background.
None of that's too much of a problem for me, as focused as I was on just getting through the game and filling out my 'dex. The linearity isn't an issue (there hasn't been a truly open-ended Pokémon game, with the original Diamond and Pearl coming closest)—it's that even with the new EXP Share, grinding is a necessity to not get wrecked by the Elite Four. Getting my team up enough to do well against Siebold was a royal pain, and it definitely made me enjoy things less in the long run.
All that said, this is Gen 6, and the Kalos games gave us some of my favorite Pokémon designs of the lot. Obviously, Hoopa's up there, but I also gotta give special mention to the Noibat line, Inkay, Froakie and Frogadier, Diancie, the Amaura line, and Goodra. (And SOME of the Megas. Mega Scizor's great.)