They aren't rationalists per se, and don't seem to overall have a high opinion of rats (though they're also willing to paint a better picture of e.g. Scott Alexander than e.g. r/SneerClub paints, so it's probably best to not confuse the two), and they're willing to get personal and ad their hominems.
However, while I'd give them less credence than Wikipedia (which has issues of its own, as we're all aware), that doesn't mean that I ignore it entirely. Maybe it's because I grew up in a cult, but RatWiki is really nice to visit every now and then, for much the same reason that I still visit r/exmormon every now and then. Also, it keeps a better list of cranks and scoundrels (and their cons and scandals) than Wikipedia, so I also use it every now and again as a(n initial) resource whenever my parents mention some person or thing which I'm pretty sure is bullshit just by the sound of it.
But it's funny, and while their sarcasm or satire might be not for everyone taste they don't exclusively attack right-wing people they do with everyone that says or does something not very smart one way or another -> https://rationalwiki.org/wiki/George_Monbiot