>A number of years ago I got the impression it wasn't a good experience (might have been the 3.x days) but Oracle has been putting some effort into it lately with the latest 4.x and 5.x branches. I've only used it on Windows, it's been pretty good.

Can't update my previous message, UT throws an "unexpected situation". Just checked the version of VirtualBox, it's 5.0.24.