The BlackBerry PlayBook tablet is a good-looking piece of hardware.

Like the proto-humans in 2001: A Space Odyssey, you’ll be eager to touch the monolithic object’s black, buttonless visage. But once you do, things get a little more complicated.

The PlayBook’s design exudes the same sense of finely honed “business chic” that Research in Motion has perfected in its BlackBerry smartphones. But the PlayBook’s software suffers from several missteps and oversights, especially in the drought of useful apps — the very things that have made tablets such a hit — and the lackluster performance of Adobe’s ...