I’m a longstanding Ubuntu user - currently on 16.04, so Unity - and was asked by my daughter to install 18.04 as a dual boot on her new laptop for university. The install was easy, but there were three gotcha points along the way that would immediately put someone off Ubuntu.
The first was the Grub boot order which at the end of installation was Ubuntu first, Windows 3rd. She sees her laptop as mostly Windows now, Ubuntu down the road, so the boot order is important. There’s no dialogue during installation on boot order. And, to some extent worse, there’s no easy graphical tool to change the boot order - it requires some fiddly command line wrangling. It’s such an important primary fix after installation, this doesn’t make for a good first experience.
Secondly, on 18.04, we discovered the right touchpad button was turned off. UX designers had chosen that a two finger click would be used instead and right button click on the touchpad was treated just like a left-button click. This is just bad UI decision - right clicks are always right clicks; two finger click is an addition, not an alternative. The options for the click behaviour are also pretty badly described so it wasn’t clear what we had to do to turn it back on. This has an immediate issue because you can’t right click on the application bar to change or add applications until you’ve discovered how to make the right click ‘proper’ again.
Thirdly, coming to 18.04 from 16.04, the first stage I want to do is make the desktop feel more comfortable - more like I’m used to. Standard settings don’t have too many options to make changes, so the ‘tweak’ package is needed. It would be really good if this was installed as standard. It used to be ‘Unity Tweak’ - it wasn’t clear that I should be searching for ‘Gnome Tweak’ this time. Everytime the UI changes I feel I have to tweak it back to get something familiar and usable, so again this is pretty fundamental.