I bought a new (second-generation) Apple TV a few weeks ago. I had a first-gen one that I liked fine, but it died, so I forged ahead. There was much to be said for having the hard drive on the old one, and I really needed the extra audio jacks for my cheap "entertainment center" setup. I don't have cable or anything, so I just have a monitor and a DVD player with a pair of Bose speakers running into the DVD player with RCA cables. The speakers are really more meant for computers. The point of this story is that I don't have a receiver with an optical audio jack, so the main huge immediate issue with the new Apple TV was that, unlike the old one, I can't use it as a surrogate Airport Express because the TV has to be on for me to get sound. I stepped outside my comfort zone and explored the menus on my TV, and it turns out I can put it into a power-saving state in which it stays on but with the screen off, so I'm doing that. I've gotten used to it, because my other options were to spend several hundred bucks on an entertainment system I don't really need or want or to buy an optical-to-RCA adaptor that costs nearly as much as the Apple TV. That's the only, although huge, negative thing I have to say about the new Apple TV.
A more minor complaint is the rental process. I use iTunes for a few TV shows, and I like the $0.99 price point, but I don't like the 45-minute wait between the renting and the watching. With the old ATV you could rent a movie and start watching within 15 seconds. With this one, what's the deal? There's no hard drive, so what's it doing? If it's streaming, it should stream. Immediately.
But mostly I think Apple has a winner with this thing. It's cheap, relatively, and for those of us who are cable cutters and are already ensconced in the Apple ecosystem it just slides right in handily. It's wicked small and unobtrusive. And it doesn't get super hot and heat up the room like the old ones did. I don't use the Netflix integration because my DVD player does a slicker job of it, but it's nice it has it. It was brainlessly easy to set up (pretty much hook up cables and turn on).
The main thing I love about it is AirPlay. AirPlay for me was one of those technologies that I heard about and thought "meh." But then I saw the new icon on my phone after the ATV appeared on scene, and I poked it, and my Rdio music came out through the TV/Bose speakers. This is jaw-droppingly cool. iPod, Rdio, and Pandora (the three apps I would like to hear music from) all play through it. It shouldn't be that much different from using the Remote app to play music to the old ATV via streaming, but there is no delay, and you couldn't use third-party apps with the Remote/streaming method. Plus, other people can play their music on my ATV. It's just really cool.
I even like being able to flash my photos from my phone on the TV to see what they look like big. It's one of those things you start using and then think "obviously I couldn't have lived without this much longer without feeling deprived."
So...it's frakking annoying about the audio jacks, but for the $99 I've gotten a handy addition to, mostly, my music-listening arsenal. Squee, Apple TV.