Why is it not great? I just opened session from cmd.exe to a Linux host and checked few things. Colors work, vim works, tmux works, arrow keys work, delete and backspace works. From a quick test the only issue I've found is input with cyrillic layout, but that's definitely not something to be concerned about.
It's slow, the clipboard integration is flaky, the resize behaviour is weird. And difficulties with non-ascii input are a serious problem for some of us.
Not sure about speed, but clipboard integration works for me from the first glance (see my neighbor answer) and resize works, at least for vim and tmux. Non-ascii input requires more research, I think that with some additional configuration it should work.
To copy text, selecting and pressing <Enter> or <Ctrl>+C works. To paste, one should right-click window title and select Edit -> Paste (Ctrl+V and Shift+Insert are sent as a hotkeys to the Linux). Or just right-click terminal window.
Another approach is to enable "Use Ctrl+Shift+C/V as Copy/Paste" in terminal properties and just use those shortcuts, they seem to work fine in ssh.
