Node 2i interface/app, a beginner's question

I know almost *nothing* about the Node 2i and have a pretty basic question. My teenage son has a decent first-time stereo in his room, and he uses Spotify on his phone connected to the receiver via an RCA/headphone jack cable. It's awkward to use and he has no way to play files from a flash drive, internet radio, etc. 

I'm thinking of picking up a Node 2i for him. It looks like he can run it remotely from his phone, connect a flash drive, play internet radio, and likely have improved sound quality.

My question is about the phone app. He's used to the Spotify design and I'm not sure what the Bluesound app is like to use. (I'm assuming that he has to use the app as a remote, not the Spotify app.) I know it can stream Spotify but I can't tell beyond that whether it's an intuitive, appealing app. The reviews at the Apple store are discouraging. Does anyone have any thoughts? Any experiences going from the Spotify app to the Bluesound app? And, since I'm asking questions, is it easy to run Roon on the Node 2i? (I've never used Roon but I've looked at the website a bunch.)

Also, respectfully, I'm not interested in considering other streamers unless they're at or below the Bluesound price. He cares less about audiophile sound quality; he just enjoys music. I want something easy and well made.

Thanks!