A whole week late, I finally found the time to watch the finale. I skipped over some bits (yes, Cadence is a bitch to the others, I get it), but it is indeed awesome. Chrysalis lampshading the 'Power of Love' as a ridiculous concept got a chuckle out of me. In every other show, she'd be right. Though the ending had still a small taste of Deus ex Machina (after they had to put Dea Celestia in the machine earlier), it made sense.
For my fanfic, if Chrysalis hadn't been introduced in this episode, I would have to have invented her. I was lacking a more personal villain and she fits the bill perfectly. Now I have to get around to write it.
Re: canon, I too was worried earlier about Cadence being an alicorn breaking previously established canon, It does, but it's handled very unobtrusively and I'm not annoyed about it. If it's a problem to you, just think of her as a unicorn.
Pony-related anecdote from German politics: A few days ago, FDP president Philipp Rösler railed against the Greens in a speech, accusing them of trying to outlaw everything not fitting into their worldview with a list of made-up examples. After he mispoke "Ponyreiten"[pony riding] as "Ponywerbung"[pony ads], the Greens did [EDIT: Has since been changed. 'Twas a large pink pony (not in the FiM style) to the right of the content, with a "Ponywerbung" sign] on their homepage.