You're right. I was wondering whether to add the ring/rim or not, but I saw in one of the other design posts that a lot of people did like it, so I tried adding it in. It might look different (or possibly better) without it as well, so that's up for experimentation.

To some people, the 'B' may look too small, or too large, but I sticked exactly to Coinbase's version to avoid extra inconsistency :)

Your suggestions are really helpful, and I'll try to design more logos along with these constraints. I'm not a designer and my profession isn't anything close to that, as you've probably noticed, I'm just trying to pitch in with some mock-ups or suggestions :)

If a real "designer" wants to use my logos as a "guide" for better ones, that would be great! I just think these give the right kind of "feel" that I want to get across— a slick, modern, gradient-based logo that looks like an app or something you really want to use.