I picked up a few copies of Interzone some months back at a bookstore going-out-of-business sale (sadness!). I'd seen the magazine before, but had remembered it as cheaply produced and not terribly interesting. But either my memory is flawed, or things have changed.
The magazine is now slickly produced and often very interesting. The two most interesting things about the issue I'd picked up were a Charles Stross story called "Antibodies" (which neatly tied together several threads that I'd just been reading about, including strong AI and the Vingean Singularity) and the Nick Lowe film review, which casually dropped off-handed comments like "the Marvel Universe is the single largest narrative artifact in human history" (quoted from memory, probably not exactly right). (Rob later pointed out that any long-running soap opera could probably be considered bigger than the Marvel Universe—five hours of filmed story a week, the equivalent of a hundred feature films a year, for (in some cases) twenty or more years.)
(By the way, "Antibodies" has now been reprinted in Gardner's latest Year's Best Science Fiction.)
I picked up a couple of other back issues, liked what I read of them, and decided to subscribe. The magazine isn't always up to the high standard set by that first issue, but it's still good and still thought-provoking, and there seem to generally be several particularly felicitous turns of phrase in a given issue. Even the letters-to-the-editor column (titled "Interaction") is fairly often interesting; my favorite line from the issue I'm reading now is from a letter by Alasdair Montgomery:
I was about to write in support of Paul Beardsley's appeal for more discussion of fiction in "Interaction" (although already I can see a flaw in that course of action) . . . .
Nick Lowe's reviews continue to be almost worth the price of the magazine by themselves, btw. And David Langford's "Ansible Link" is also a lot of fun, particularly the "Thog's Masterclass" sections, with dreadful quotes from published fiction.
Interzone keeps showing up on the Hugo ballot in the "Best Semiprozine" category; I'm not quite sure why it's considered a semipro (circulation? Pay rates? They don't pay by the word, but dividing their pay rates by preferred wordcounts suggests that they pay more than the British equivalent of 3 cents/word for most stories), but imo it stacks up well against the print prozines.