Yeah, I'm fond of the AppContainer sandbox in a way; I think most consumer applications can get by in a sandbox (my UWP app could), and sandboxing applications can be empowering for users since it lets them run more code without worrying about trust.
Unfortunately, the execution was a mess. Not having any way to opt out of the sandbox was an insane decision and it led to crazy workarounds; even first-party Windows software has to do things like ship a sidecar exe to bypass the sandbox (the Store does). And troubleshooting issues with the sandbox was a pain, configuring capabilities was a pain, and there was very little in the way of iOS-style user-facing permission controls.
And don't get me started on the marketing; MS flacks kept telling devs how sandboxing benefits users while doing virtually nothing to convey those benefits to users.
Unfortunately, the execution was a mess. Not having any way to opt out of the sandbox was an insane decision and it led to crazy workarounds; even first-party Windows software has to do things like ship a sidecar exe to bypass the sandbox (the Store does). And troubleshooting issues with the sandbox was a pain, configuring capabilities was a pain, and there was very little in the way of iOS-style user-facing permission controls.
And don't get me started on the marketing; MS flacks kept telling devs how sandboxing benefits users while doing virtually nothing to convey those benefits to users.