Yes, although for me, it's not characters but the relationships between them that catches my eye (usually). So it's almost inevitable with most shows that it's going to take a few episodes to build those relationships to the point where they really snag my interest. And a half-season to a season is usually long enough for me to get a good idea whether the show is going to "grow" the relationships in a way that is appealing to me.

The shows that have hooked me in the first few episodes have usually done so on the basis of catchy, compelling plots and intriguing mysteries more than characters -- Fringe and Lost come to mind as examples. (Or humor ... I kept watching Community, for example, because it was funny. Even in a drama, a little humor is a big mark in its favor; all serious all the time will usually lose me too.) In Fringe's case, I liked the writing enough to keep watching even though I didn't really warm up to most of the characters 'til the second season.