I started watching Nowhere Man, like many people here, because it came on after Star Trek: Voyager, and my interest in the former soon began to eclipse my interest in the latter. I didn't catch every episode (given its obvious quality I assumed I would have ample opportunity to watch it in reruns) but the ones I did see had a huge impact on me and I was lucky enough to see the final episode.
Nowhere Man is the kind of show you need to discuss with other viewers, but I can count on one hand the number of people I've met who remember it and inexplicably none of them cared for it. I was totally nuts for the show when it was on the air but I was much younger at the time. Truthfully, over the years I had worried that it would not live up to my memories.
Finally, Nowhere Man's single season has been released in a great 9-disc DVD set, and after 10 years I've truly enjoyed the chance to rediscover each of the 25 episodes. It's just as good as I remembered (and even better in some cases), with only a few episodes that don't quite measure up to the rest. Bruce Greenwood's performance is incredible. There is literally nobody else who could have made Thomas Veil more human. He makes even the silent moments a fascinating pleasure and basically carries the entire series. That's not to suggest that there aren't great performances from other actors, but Greenwood is the keystone of the show and he handles the weight effortlessly. You don't see acting of this quality on television very often. The writing is consistently solid and smart (though as I mentioned there are some "off" episodes), and Mark Snow (of The X-Files and Millennium fame) provides a wonderfully varied, appropriately moody soundtrack.
The bottom line: if you're a fan of The Prisoner (which strongly influenced the creator of the series) and/or The X-Files, you owe it to yourself to give Nowhere Man a chance. It's hard to believe that a show this good was canceled and it's harder to believe it graced a channel like UPN. At least we got one great season out of it.
