It also doesn't help that what should be the main event of these reviews - XKCD - is so well known that any actual serious attempt to review it would be fairly much superfluous. As far as I can tell, XKCD succeeds through its lack of compromise. As far as the art goes, you'll get stick figures and be thankful for them. As far as the writing goes, you'll get mathematics and esoteric physics and be thankful for them.
More often than not the results are particularly good, and quite often funny as well as thoughtful. For stick figures, XKCD's stick figures are cleanly drawn and it's obvious what they represent; for example, for all that the seated character in this comic is a stick figure, she still manages to uncannily resemble my mother (as has previously been commented to me).
If this comic has one flaw, it's that sometimes its references are just too advanced. This comic was pointed out to me as one that just wasn't funny. I actually got what the writer was trying to say; although I couldn't actually have named them, I was aware of the concept of Von Neumann machines. A possible annoyance could be that quite often the funniest line in a comic is the alternative text to the image itself, which on some browsers doesn't always show correctly (Both Internet Explorer and Firefox play up; Firefox only shows the first few words if the text is particularly long; and in Internet Explorer the text only shows for a few seconds before disappearing. Both of these are really more browser problems than problems inherent in the comic, though.
Brief notes on other comics recently read and enjoyed:
Sandusky is the story of a man and his cat. Not anything like Garfield, though; the cat in question after whom the strip is named is a mountain lion (sometimes also referred to as a cougar; I'm not well enough educated in such matters to know whether they are one and the same) that got dropped on Not Jon's doorstep as a kitten and... grew. A lot. At the moment the strip appears to be auditioning for newspaper syndication; for the last few weeks it's been presenting a daily black-and-white strip very much in the newspaper storytelling style, but most of the archive contains a continuing story of Sandusky and his adventures.
There's another major difference from the standard pet comic (Garfield, Footrot Flats or even Peanuts when Snoopy is on camera) and that is that Sandusky and the other animal characters can communicate perfectly well with humans, like the animals in Bloom County, which raises questions about the whole concept of the keeping of pets in this particular universe. But overall it's an entertaining if undemanding read.
Dungeons and Denizens is nothing but good fun, following a young minotaur on his first days on the job as tech support in a traditional Dungeon (capitalisation deliberate) where all the monsters, demons, evil wizards and suchlike are on the clock and have a job to do. Cerberus' two-headed daughter does tend to steal every scene she's in, mind you; four big puppy eyes are even more dangerous than two.
Theri There is primarily An Educational Comic about the "Otherkin" sub-culture, the existence of which I am aware of but of which I am not a member, but also features some very nice line art which is its main attraction as far as I'm concerned. This one here is probably my favourite piece of artwork; but it should be pointed out in case anyone with an interest in the subject is reading this that the 2007 seasonal instalment is scripted in Quenya (and Fëanorian) and subtitled in Roman (and English).
Freighter Tails and Carry On are two of the comics which supply characters who are used out-of-continuity by Cross Time Café; the latter is a decent if undemanding soap opera, while the former is a space opera with an interesting start but which doesn't seem to have been updated for a long time. Lupus is a werewolf story, just starting out and with a particularly original art style. Quest of the Therian Urn follows a group of people who have been cursed into permanently changing shape (and species) and have decided to embark on A Road Trip and try to break the curse at the same time. Fur Will Fly and its sequel, Coming Up Violet, follow a regular... well, not to put too fine a point on it, idiot... as a freak dimensional thingy lands him in a universe of anthropomorphs. Most of it's fairly light, although there's a werewolf story which is done quite interestingly. Unfortunately, the author seems to be unaware of the existence of the Tasman Sea...