Yes. ESXi is it's own base operating system. By doing it that way, they've assured that the VM's have much more control and access to both the physical hardware and resources than they'd have if running underneath another host OS, such as Windows or Linux. It's really very easy to install (bootable cd image,) once you have hardware that supports it, and installing and managing guests takes very little understanding, as well. There are a few options you might spend some time on, with some of it's internal routing configs, etc, to give hosts NAT, Bridged or internal VLAN's, but aside of that, I think you'll find it very easy to work with. The ONLY drawback to it, at all, is that there's a bit of effort involved if you want to transfer, say VMWare Workstation VM's to the server, or vice-versa, as there's a bit of translation that occurs, however, if you truly want a server, it's not as likely you'll be moving VM's around.
IF you plan to run the VM's where you can 'easily take them with you,' then I'd advise VMWare Workstation (which I've also been running since VMWare's earliest revisions.) Now, it does run under a guest OS, so hardware access is more 'tainted' based on what the host OS allows the VM's to do, etc, but VM's are easily portable between HOST machines, and even between multiple HOST OS's (such as Linux and Windows) with only minor tweaks involved.
So it ultimately depends on how flexible you want to be, whether or not you want a system that's very similar to what larger, production customers run, and what type of hardware or portability you want. Regardless, I prefer VMWare to the other options. It's always just been way simpler to get things done, way more functional, and again, tends to be status quo for customer environments I've been in.
~ hayabusa ~
"All men can see these tactics whereby I conquer,
but what none can see is the strategy out of which victory is evolved."
- Sun Tzu, 'The Art of War'
OSCE, OSCP (Former - GPEN, C|EH - both expiring / expired)