Those fans most interested with the mysteries/mythology of the series will be somewhat disappointed as many important questions (the numbers, lack of fertility, MIB and Jacob’s real identities, the Dharma initiative sponsors from MI, etc.) have been left unresolved.
Put me in the latter camp - probably due to my math/science background and interest. I'm not content to just accept what happens in my surroundings with no explanation, and only focus in on the people around me, since I'm not really that much of a "people person." I want to know why things around me happen - the rules of the game, the physics and rationale behind the environment I live in so I can understand it and potentially use it to my advantage. The physical universe and rules governing the island were NEVER explained. For me, no closure at all. A very frustrating show.
The writers were definitely more in the "man of faith" vs. the "man of science" camp, effectively thumbing their nose at science fiction fans. They might as well have had the Keebler Elves living in a tree somewhere on the island, populated it with unicorns and dinosaurs, or had the castaways be visited by Santa Claus. Would have made about as much sense.
I agree somewhat as like you I was more interested in the mysteries/mythology/sci fi material. But the characters did make the show very entertaining and while I’d really like to have an explanation of MIB’s/Jacob’s mother, how the island “moves” through time and space, etc., I think if they did try to explain them they would just fail and then we’d complain about their lame explanations. Perhaps better to leave the more complex ideas to our own imaginations, ha ha ha.