I'm catching up with the end of season five on the Lost Website. Can't wait to wrap this show up. I got hooked on it earlier this year and blew through the seasons via the video store, Hulu, and ABC's video gallery.
I too started watching it on Hulu and Netflix in the last six months or so and quickly blew through all five seasons! It's certainly addictive television. I do think it struggled after the first couple of seasons. It has the same problem other shows with long unfolding mythologies have had - the writers have to keep stretching it out to fill the episode order, and things get so convoluted it actually doesn't even matter what happens since nothing is ever conclusive, even death. The suspense starts to suffer when you realize most events don't have any ramifications.
That said I will definitely be watching in February It's still great cheese TV.