Maybe it's because I grew up reading super-hero comics, but I'm a sucker for serialized storytelling. However, I'm always a little wary when it comes to tuning into new TV-serials.
For one thing, most TV-serials are cancelled before they can wrap-up all their storylines, and I have a hard time investing time in a show if I suspect that it's not going to be around very long. Sometimes I go ahead anyway, as is the case with the ABC teen comedy/soap opera life as we know it, which is based on this YA novel by Melvin Burgess. The show has a lot of things going for it: it's well-acted, funny, and it handles its more melodramatic moments extremely deftly. Going against it: it's hardly groundbreaking, and even though it's a less preposterous show than stuff like The O.C., I'm not sure that it will be able to find an audience. It's more likely to go the way of My So Called Life and Freaks and Geeks, which resemble life as we know it in everything except their self-importance.
On the other hand, going on too long can be just as big a problem as stopping too soon. For example, I already have my doubts whether or not the people who make Lost can really drag their plane-crash-survivors-on-a-haunted-island story on to the end of this season, let alone the next one they're presumably hoping for. (And even though I enjoyed the first two seasons of 24, it really seems like a premise that shouldn’t have been repeated).
The final problem is that it is very difficult to sustain the right tone, mood, and style over the course of an entire season. I’ve had fun watching Desperate Housewives, so far, but I think that the show is almost always pretty close to the line that separates "campy guilty pleasure" from "just plain crap". And I'm kind of amazed that the few second season episodes of Arrested Development have been able to recapture the screwball style of the first season. (Success is perhaps the great sitcom spoiler).
Now, all these issues relate to the one of the peculiarities of American TV: that most serials are intended to be open-ended and (potentially) everlasting. British TV has a greater variety of formats for their serials. For example, The Office was a serial comedy, with two seasons of six episodes a piece, and two follow-up "extended" episodes, all of which told a complete story.
Why don't we have more series like tha--that is, shows that are somewhat longer than a special-event-style mini-series but with a definite beginning, middle, and end--here on American TV? Well, the market has a lot to do with it: with so many channels and so many choices of what to watch, TV shows need to last long enough to develop a kind of brand name strength to attract big advertising money. Long-lasting shows can be counted on to deliver an audience week after week. Of course, there's a kind of Catch-22 here, because most shows don't even get past the pilot stage, let alone last for multiple seasons.
There's slightly more variety in serial format on cable: HBO's Band of Brothers was a kind of maxi-series (to borrow a term from 1980s DC comics marketing). But even Band of Brothers was sold because of the star power behind it. While it might be possible for an up-and-coming TV creator to get a traditional kind of show on the air, it's not that likely that any TV network or cable channel would get behind a serial with this kind of maxi-series, beginning-middle-end format.