$35 and let's me use my phone as my remote for Netflix, HBO Go, and Hulu. Drop dead simple casting. Also it doesn't stream from the phone; it simply takes in commands so it might save your battery some.
Then, I gave away my Apple TV and bought a Chromecast. Searching for content.. jumping between content sources.. it's all easier on the phone.
What I like about Chromecast is that their integration is simply a small button added to other apps that I'm already familiar with.
For example, I use Netflix as normal but basically choose where the output should go. It's actually quite similar to Apple's AirPlay integration although the Chromecast has never had an issue (AirPlay always seemed to have latency issues).
Not if you want to pick what to watch with someone else.
Bad argument. Any remote control can run out of battery.
But moreover, when your phone dies and you're using it as a remote at home, you likely have the charger right there are home too. When the AAAs in your dedicated remote die (though PERHAPS more infrequently) you need to go running around to see where you shoved that container of AAAs, find that they're all actually the dead ones, and then go to the store.
Battery is only the second worst part about using a phone as a remote, the worst being that a phone is anti-social while watching television (on a television) is social.
If your remote has a keyboard on it then more power to you, but none of mine do, and the phone is 1000x easier.
For my money, the best remote I ever used was the original TiVo. There's something a lot more haptic about a physical remote with real buttons. And I have yet to see a Chromecast remote app that's very good. Where's the dedicated "skip back 9 seconds" button? Or "turn close captioning on"? These are things I do all the time while watching shows.