I bought Roku two years ago and eventually gave it away and now I bought another one, the $99 one.
I hate it. Absolutely hate it.
The thing has the worst software I have ever seen. It literally feels like a college kid wrote the software. Every time you press a button you have a ~full second pause before it responds. Even the remote buttons are poorly made. For some reason the picture quality is terrible, horrible. The same content and apps look better on the Apple TV on the same TV using the same WiFi.
A great example of why I hate this product is Angry Birds. The controls are fine, the game works fine. BUT. The game looks like the Roku is using a VideoOut cable from 4inch-screen phone to a TV. And this is a featured app. The private channels are worse. The private channels are the reason I bought it, CNN Int, Al Jazeer and Aereo. They ALL look terrible.
Errors. There are always errors. I don't use Netflix or Amazon on the device but the other stuff always has issues and just does not buffer well. Again, the same content on the same network on the same TV work fine on the Apple TV.
The Apple product is so much more satisfying. The device response is instant, everything looks beutiful. It is easy and intuitive to navigate. Air Play is great. If you have mirroring from a mac it's even more content. If you live in the Apple ecosystem I really think it is a must-have device.
It's a shame because some of the developers did a nice job with what tools they had.
I'd say you have a bad Roku because all 3 that I have had are fast and snappy..
My Apple TV rebooted far more than my Roku did and as far as the remote goes, I think most people loathe that pure junk of a remote that Apple includes.. The Roku one is not much better, that I agree with.
As far as angry birds goes, the game included for free is the SD version. You have to buy the HD version if you want it..
Angry Birds, or any game for that matter, is non existent on the Apple TV..
I've had 3 different Roku's and have had none of the issues you write about..
Yes some / most of the private channels are SD but that's not Roku's fault. Try writing the developer of the channel and ask if they can add an HD stream / channel..
While some / most private channels on the Roku may be in SD, at least you can get them. Good luck with that on an Apple TV..
My .02