Creator/s: Marc Blanco
Run: 3/10-9/10, 9/13-current
Schedule: Usually daily
Website: Tumblr isn't really meant for hosting webcomics. The comic has a better Smack Jeeves site, but only a few strips have been added to it. In any case, both sites are just boring, generic templates.
Writing: I argued in my review of Wayward Nonsense that the creator's whiny avatar was too immature, narcissistic, and neurotic for readers to relate to him. However, that character occasionally had some positive experiences, particularly when he was alone playing video games or watching TV. John the Sketch presents a similarly dysfunctional creator-avatar, but, here, pleasant moments are almost nonexistent.
The creator's idea of telling jokes is whining about how unhappy he is. He whines about living in Britain, living in the Netherlands, being homesick, the bad weather, not getting to ride his bicycle enough, not having a job, being poor, his house being too small, his house being dirty, having bugs in his house, not getting to sleep in enough, not spending enough time with his girlfriend, feeling awkward around tall people, not being able to speak or understand Dutch, technology, tourists, getting spam e-mail, not feeling creative enough, people not understanding his comics, feeling depressed, feeling lonely, having suicidal thoughts, his soup being too hot, his soup being too cold, pressure to conform in society, being out of shape, and whatever else I didn't mention here. Not only are these strips boring, repetitive, and unfunny, but they're so overwhelmingly negative that I felt depressed and irritated reading them. If the creator's goal is to entertain people, then he's failed completely, and if he's just trying to cope with his depression, then he should be getting professional help instead of using his webcomic as self-therapy.
In addition to the strips about the creator's misery, there are some that barely make any sense, and the creator seems to lack basic storytelling abilities. Instead of a standard setup-to-punchline structure, the strips' formula is what I would describe as "something happens." A good example is this strip, where there's no context or joke; the "something happens" is "John rides his bike in the rain." And in this one, the "something happens" is "John punches some dude with wings." And for another example, here's one where the "something happens" is "John flies." Then, you have the one-panel strips, where the "something happens" is stuff like "people are standing" (here), "John is depressed" (here), and "someone is yawning" (here). And, for some reason, there are a couple political strips written in Spanish, which should have been translated. The panels aren't being used efficiently at all, killing any potential that some of the gags may have had.
Art: The success of Cyanide & Happiness, Dinosaur Comics, and xkcd is one of the worst things that's happened in the webcomics world, as droves of inexperienced webcartoonists have been drawn to minimalism without understanding how it works. In the webcomics I listed, blank backgrounds and simple non-characters are used to place emphasis on the dialogue and text. In John the Sketch, though, there's usually little to no text, which means that it's the comic's crude artwork that's the emphasis of the strips.
I'd be a little sympathetic if the creator couldn't draw, but strips like this, this, and this show that he's actually a capable artist. These strips are all from 2010, though, and the quality's only gotten worse and worse since that point, with the most recent strips being some of the ugliest inked work on the site.
Overall: John the Sketch is a terrible comic strip, and it's only been getting more incomprehensible and minimalistic as the creator's depression seems to worsen. The relentless displays of misery have no clear purpose, making this comic a complete waste of time for both the creator and anyone who tries to make sense of it. Considering that all of the strips involving art are negative, does the creator even like making his webcomic?