I own two Weber kettles, both in 22" size. My main one is about 5 years old, it's a Performer (the one with the built-in table/frame), and one from the late 70's, a "Bar-B-Kettle" (these have heavier lids, and 3 bottom vents (as opposed to the new style with the ash-removal/vent system; it's easier to control heat with the old style, IMO).
For $90, I can't see why more people don't just keep one around, even if they own a gasser. The control, and ability to cook in so many different ways is incomparable to any gasser. If you jump into charcoal cooking, buy the 22" model, not the 18.5". It's exponentially a far more versatile machine for $20 more.
And once charcoal cooking becomes sorta instictive, I can have my food done in only about 10-15 minutes longer than with my Weber gasser. But really, it's the ability to smoke, and the control I have, which keeps my gasser relegated to collecting dust.