If you want to call that the afterlife then so be it but the island wasn't it.
The final shot was the airplane still on the island, broken into a million pieces and grown over with vegetation. Not in one piece, and definitely not flyable.
Also, if they could have just backed out and flown away, why did this series last so long?
As far as the music goes itís obviously a matter of personal taste but Iíve always found the music on Lost to very evocative and perfectly suited to the series.
If it was always that bad... well, I don't like most Spielberg pictures for the same reason.