Threshold (Braga version)
Started slow, got cancelled just as it was getting good and just as its arc was really shifting into high gear. A missed opportunity, but had worthwhile elements.
I'm lukewarm on this one. I wasn't crazy about the first two seasons (counting the original miniseries as a season), and while it got better, it was always mixed in quality. But it did have some very good episodes.
Deep Space Nine's Ira Steven Behr was the showrunner for most of its run.
I really liked it at first, but got fed up with it partway through the second season and gave up watching. Initially the characters seemed to be on journeys of redemption, but then when the show became a huge hit, the network wanted to drag it out, and all the characters' journeys were reversed and they were stuck in holding patterns that became tedious to watch. A lot of people still loved it, and I've heard it said that it got better later on, especially once they settled on an ending point and didn't have to vamp for time anymore, but I never got back into it. What I've read and heard about the finale leaves me with no interest in that.
Seasons 1-4, run by creator Aaron Sorkin, are magnificent, one of the best TV dramas of our generation. Those who are staunchly conservative in their political views might disagree, though I always felt it was fair to both sides, and was more about favoring intelligent, well-intentioned governance over petty, self-serving politicking and propaganda than it was about favoring left over right.
Seasons 5-7, made without Sorkin's involvement, are a totally different show. Season 5 is the absolute nadir of the series, a directionless mess. Seasons 6-7 recover somewhat but tell a very different story largely focusing on new characters (the candidates in the presidential election and their staffs), and the established characters aren't the same people they were. Those seasons aren't on the same level as Sorkin's writing, but they're not bad, and in a lot of ways they were startlingly prophetic about the 2008 election.
Brilliant first season, but it fell apart after that. The original plan was to follow different characters each season, but the first-season cast was so popular that the network insisted on keeping them around, so the writers had to try to perpetuate the stories of characters whose journeys had already been completed. Also they lost their best writer (Bryan Fuller) after the first season. The second season was mediocre and was shortened by the writers' strike. The third season was incoherent and awful. The fourth season recovered somewhat and had its merits, but was still nowhere near the heights of season one.