While the first two seasons were watchable, I felt the show really hit its stride this season, with the third best season of the series.
Episodes That I Liked
There were five episodes that I ranked 5/5, four of them with a “heavy” Desmond role in them dealing with time-travel and trying to prevent Charlie’s death: Desmond feeling the weight of his pre-cognition (E08); trying to save Charlie while Claire is trying to figure out what is going on with them (E12); Desmond faced with endless choices where none of them seem right (E17); and Charlie remembering his five greatest memories (E21). The other “5/5” was early on with a prison break where Juliet is ordered by Ben to help (E07).
I ranked nine episodes as 4/5, including Eko looking for his brother (E05); Kate’s romantic history (E06); Jack living with the enemy (E09); a history of Hugo’s luck (E10); Locke playing chess at a new Dharma station (E11); Locke dealing with his father’s betrayal (E13); Juliet’s backhistory is pure and clear until the Island (E16); and the two-part season finale (E22 and E23) with the visit to the underwater station.
Episodes That Were Watchable
After you get through the fourteen episodes above, the rest were all 3/5 for me: Jack meeting Juliet (E01), Sun lying to Jin (E02), Hugo having déja vu and understanding Desmond (E03); Desmond trying to save someone (E04); a “lower decks” storyline about diamonds (E14); Kate making a friend (E15); an ultrasound for Sun (E18); a bad day at Black Rock for Locke’s father (E19); and Ben basically being Ben (E20).