Heroes and BSG earned my frustration and ire. Both shows tanked brutally and became horrible.
For whatever reason, I'm still on board with Lost. The plot holes don't seem as glaring. Things add up for the most part. It's entirely a ridiculous show about a magical island, but at least their inner logic makes some sense, you know? I don't feel like they "make it up on the fly" as much as those other series.
There was only one point that I really had to roll my eyes at the show. It was when little Ben Linus was shot by Jin and the "others" took him away and said, "if we take him.. his innocence will be lost... and he will remember none of this". OoOOoo... how convenient! That use of deux ex machina was the only point where I felt like the writers copped out. The rest of it, I can live with (so far).
I can even live with stuff like Locke coming back to life, because I feel like the show set a precedent early on in the series with Jack's dad...
But the Linus "he will lose his memory" thing was just weak.