It's gotten a lot better, have you used the iOS9 app yet? Or I would imagine the Android app, their latest update on iOS is pretty good. While you are still using their app and spinning up a browser inside it, it doesn't feel that way anymore, and this is coming from someone suffering the pains of using this on an iPhone 4S.

The Android app is not particularly good, but it gets the job done. Much like the Windows client compared to Mac, it's clearly playing second fiddle.

They're doing a new "Windows Modern" (or whatever it's called) version, I need to give that a try sometime.