I think this site is invaluable for use with the Top Webcomics list. The list is helpful finding webcomics you otherwise wouldn't ever find out existed, the voting is helpful in that as long as a comic is picking up even a handful of votes, it's probably still online (beyond the first 1000 or so, it's a veritable forest of dead links for the remainder of the 8550+ listed) and this website is very helpful in that some of the comics attracting votes are here and for good reason. The forum posts on probable vote fixing were very interesting.
On the flip side, good reviewing is an art in itself and can create even further entertaining material as an extension of the original work. Even if I like the work that's being criticised (and sometimes even being taken down viciously), a well done review can add to the enjoyment, both in its own right but also of the original material. It can also raise interesting points about the flaws and even alternative directions the material could have gone that I'd never have thought of. In a nutshell it can both entertain and make you think.
Also the forums are very informative, I'm working my way through Dr McNinja at the moment (haven't reached the twist yet though) and I doubt I would have ever thought to read it (or even found it) without this site and it's the funniest thing I've read in a long time.
Mind you, some of the things getting votes on Top Webcomics can fall through the cracks. I saw this: "Sam the Black Knight", saw it had a respectable handful of votes and read this: "Modern student Sam wakes up in the body of the Immortal and Evil Black Knight in the fantasy land of Denada. He is hunted by Good and Evil as he struggles to remain sane.", so thought it'd be worth a quick look. However, I didn't really fully register the significance of this bit "Graphical sex and violence R-18.". After a few pages, I'm surprised my eyes didn't start bleeding. I'm one of those people who hate to be the one being critical of other people's work (yes I know, so why am I here) as I know how much work even something objectively bad can be but this one is frequently just ghastly.