The first series of Lost kicked off with a bang... literally and slowly decreased in pace. This may have put some viewers off and people who started to watch halfway through would either be bored or just plain confused.
I would advise people new to the world of Lost to simply watch from the beginning and don't get pt off by the slower episodes. The acting throughout is excellent but why have 5 series' planned... WHY??? All this means is that there will be no answers for at least 4 years, oh well, i'll keep watching if it keeps the tension up and dialogue flowing.