The CEO of Roku said in an interview on a podcast that their goal is to keep the build of materials needed to run the software under $25 for the TV manufacturers.
They do a damn good job. Sure opening an app takes a few seconds and apps tend not to do much to save and restore state when re-opened (the app developers could do more of that, if they cared to) but the experience in any given app is usually pretty smooth and snappy, considering what it's running on. It's a testament to how good UI can be even on fairly low-end hardware when you're not fundamentally screwing up performance, repeatedly, over several levels of abstraction.
On one hand, for a smart TV platform, there are a lot of positives. First and foremost it’s Switzerland. It’s neutral and everything is available for it - amazingly enough even AppleTV. As you said, the interface isn’t bad given the hardware constraints, and they support their hardware as long as feasible. I had a few Roku boxes back in 2011. I have three Roku TVs and will probably have two more by the end if the year. I also bought my dad one.
On the other hand, I hate the ads that take up half the screen and the hard coded buttons. The UI is decent, but not as responsive as my AppleTV 4K.
