There have been people online however who have had less-than-optimistic comments about the finale, and all of season 6 in general. They say that the season answered no questions and gave no resolution. Basically a lot of the comments have said that the writers took an easy out with having everyone be dead in the end. There have been a lot of people (myself included) who have defended the finale in all its glory. One commentor wrote, "I dare all of you to wikipedia 'McGuffin' and enlighten yourselves."
Okay, so basically a McGuffin (or MacGuffin, whatever you prefer) is a literary device used to motivate the characters, while the main plot is really happening. On Lost, the McGuffin is the Jacob vs. MIB struggle and everything that surrounds it. In other words, the island. It is the driving force that motivates the characters' actions but really the main plot is happening under the surface. The main plot of Lost is the people. It is how these people came together and helped each other to overcome the issues in their lives and "let go" as Jack's father said. In the framework of the show, the plot is the story of how all these flawed characters were really lost until they found each other. So even if "the light" wasn't explained (even though it doesn't really need to be, it's the source of life hence the island's magical ability to heal, the inability of mothers to give birth after the light had been tampered with, etc.), the main plot of Lost is still intact.
So those are my thoughts on the finale. I don't necessarily want to go into too much explaining because I really think the finale needs to speak for itself. Once again, I thought it was a beautiful end to an amazing show that I and many others have basically grown up with. I hope you have enjoyed watching season 6 and my Lost blog. Thanks for hanging in there and I would really like to thank Megan and Ashley for working so hard to catch up on seasons 1-5 so they could watch it for me. It meant a lot to have everyone on this journey together. Good luck to the future endeavors of the cast and crew of Lost! We'll miss you!