It started very slowly this year. The second episode of this season was their worst yet. Nothing happened in the present or the flashbacks. If you are going to introduce a shark, you need it to do something. I'm not saying it has to eat anybody, but it has to meance the other characters. Neither Michael nor Sawye seemed particularly frightened by the shark and even left their legs dangle in the water.
After that, the episodes have improved and it has returned to its greatness. I think the last episode's final minutes were brilliantly staged. If I hadn't accidently read some spoilers, it would have been very shocking.