Ok, I'm hesitant to say this, but the first three episodes of The Sarah Connor Chronicles have been pretty awesome, despite my strong expectations to the contrary. It could easily go steeply downhill from here (after all, the first 1¾ episodes of The Bionic Woman weren't bad either) but so far, it really has me hooked.
(Normally I expect the first two or three episodes of any TV series to suck, since usually the writers and actors haven't figured out what they're doing yet, and those episodes are chock full of exposition of the backstory, which always makes for terrible television. So it took me by surprise when BW started off ok and then immediately ratcheted up the suck.)
(Extremely minor spoilers:)
Sarah's character seems a lot less crazy and homicidal than she was in T2 just after she broke out of the asylum, but it is set four years later, so I can buy that maybe she mellowed a bit. John is still a whiny little bitch, but that's exactly like in the movie. I'm glad they seem to be setting up a long arc story and not the obvious "Terminator of the Week" plots. The River-800 is awesome, even though she's totally typecast now. I'm liking the half-Mulder-half-Scully FBI agent too ("Oh, didn't she tell you? It's because of the robots. The robots from the future.") The Oppenheimer stuff was great, and I enjoyed the shout-out to the Singularity.
And I really liked that they used time travel to delete the third movie in its entirety. That was a very, very, very good decision.
I expect to hate the high school subplot, but we'll see.
Here's a page with a decent breakdown of the timelines and timeline-revisions of the various Terminator movies: Terminator Wiki. It's not nearly as obsessively detailed as the Back to the Future timeline, which is surprising, but it lays it out pretty well. (Both of these would be easier to follow with a graphic; the BttF page used to have a chart, but it seems to have been deleted.)