This episode had a little of everything needed to a Centric - Character episode.
If you expected some revelations because this is the season finale, than probably you will hate this episode, because the mysteries are all for the long run and not about creating in every season new mysteries and than in the end resolve them.
Continuing, someone dies and of course is very easy to guess who. Jin flashback impressed me, since we have a revelation, poor Jin, after this, you can understand better his atitudes. Equal is Michael flashback, now you can understand why walt was behaving that way to Michael before.
Someone blowing up created the necessary tension for Jack, Kate, Locke and Hurley, but the only thing that I liked, was that we finally saw what is the monster, you can´t guess until you see it. This also explain what locke did before with this "Monster". But this time, they fight this strange thing.
The revelation about the French Woman and Claire was nice too.
Charlie flashback for example show how much the character evolved. But he found something that he is supossed to find. Hurley flashback was more funny.
The interations in the Raft was nice, but nothing really special, until the near ending, with provided a great cliffhanger.
Even the Hatch continues to be a mystery, but now is open and all this give you the reason to see Season 2.
Overral, some reflection, reveling and informative flashbacks, with opportunity to see the "monster", someone blown up, nice interations, Twist, cliffhanger and a mystery, make this episode only deserve a 9.