That was more of a generic"you" than directed at you, personally, Liam. I should have specified.
Yes, it's big. But it's built to be used for years in the Real World, not dicked around with in a VM for four or five hours. It has a complete development environment, several GUI environments, etc. etc., and all the source for everything included ... not all of which is required for a complete, functional system. Get rid of those you don't need (easy to do in the installation procedure) and it becomes much slimmer.
With a little effort and customization, you can make the initial install very small, and very clean, with just the tools that you, personally need/want. I have an installation script that generates the system in use by my Wife, DearOldMum and GreatAunt and quite a few other functionally computer illiterate people. It is about 8% of a full install, and I could probably cut it down quite a bit further by removing some admin tools that the users involved will never even know exist.
Ozan pointed out Eric's mini installs in an earlier post in this thread. One could start with one of those and customize it for one's own needs.
Much easier and more recommended, find a cast-off computer that nobody wants anymore. (We've probably all seen one or two year old computers sitting by the side of the road ... ) Wipe the poor thing, and install Slackware on it. In this modern era of multi terabyte drives for under one hundred dollars, 16 gigs isn't really all that much to complain about ... especially when that 16 gigs is all functional and doesn't contain spyware, ad-ware, or other malware. Use the same machine for other distro reviews. That way you'll be reviewing them in their native habitat, instead of in a constricted VM, which will obviously colo(u)r the opinion of the user.
Or, depending on the tax laws for such things in the country you are living in, purchase a dedicated computer strictly for reviewing OSes and software. Use it as a write off, a necessary tool of your chosen trade. Worked for me back when I was reviewing commercial PEE CEE UNIXes for <redacted>.