How are you finding 18.04 so far? We run several 16.04 VM servers for various purposes, just curious at this stage.
Bare in mind, my usage is as a desktop, not as a server, so I have a DE and focus on services/processes that aren't actually going to be beneficial to the server environment.
From a desktop use using the KDE setup, even though it just came out, it seems very stable. Been using it all weekend with Krita, coming up with sketches for stock designs and of course configuring the look/feel of it all (KDE's strongest point, is also it's biggest con as well, too many configuration options).
If you are running a desktop OS as a server OS, you'll like the baked in "minimum install" option. That'll take a lot of software out that you may not want that takes up resources using it as a server. The server versions of Linux that I run tend to be headless (when directly plugging into the server itself) and I have a web-based GUI to do most tasks. Although I say web-based, it
does not have access to WAN.
For me, it's been very much worth the upgrade, but again, my use has been focused towards desktop use. Contrary to general popular opinion, it is very easy to get going and use.
As an aside, while there are other considerations that I wouldn't advocate Linux for (ease of use or lack thereof isn't one of them), I find it strange that people would say to keep away from Linux if used to a Mac, considering Mac's BSD roots (kernel and user space layers derived from BSD code), they are actually quite close to one another. One of my favorite PDF print drivers that I use is actually an Apple product called Cups-PDF. They aren't as far apart as people think. I mean come on, even the terminal in Mac is bash, which is what Linux uses. It's not like it's the Mac version of Cmd Prompt (or when I was growing up MS-DOS prompt). Pretty much same commands. Now while I mention the terminal, a lot of Linux distros (elementaryOS being the one (and one that looks like very close to Mac out of the box)) don't require the user to use the terminal for day to day work and some (that one included) actually try really hard to make it to where people don't even think about touching the terminal at all. Like Mac, you will need it for advanced configurations though (if I want to get nitty gritty with the baked in Wacom driver support (something that Windows and Mac do not have from the get go), I have to use CLI (which I created bash scripts for to automate the process). But they do have a GUI Wacom front end that you can install as well. Speaking of Wacom (which is something that a lot of us use I'm sure), they have 4 full time devs that work on Linux support.