I haven't seen it since 2007, but the fact that things escalated so quickly I thought was interesting.
That said it certainly wasn't perfect, I do remember the whole thing with the British chick was cheesy (but at least she got naked) and they did arguably kill off Doakes too early, but like I said, the fact that things escalated so quickly was exciting, even if it did maybe hurt the series in the long term.
That said, season 1 and 4 are the overall best, season 4 was so fucking good that it really breaks my heart that it was all downhill from there.
Really, Dexter should have had a fairly brief run for quality over quantity's sake, but they're effort to pad it out really hurt it, but see that's why I've never quite connected with TV as a medium like most people, I like stories to be more planned out, not beholden to ratings.