If you liked Lost then there's a strong chance you'll like FlashForward too. It's so clearly influenced by Lost that you can almost picture the TV executives sitting in a meeting saying 'We need to commission another Lost and fast!' Some of the same actors also feature, as if to reinforce the connection.
The premise is certainly highly intriguing: what if you knew your own future at a specific point in time? How would that make you behave and think? It's definitely a good programme in its own right: fast-moving, slick production, some good characters. However, there are too many strands and aspects that are overlooked for me: for example, the actual impact of the whole world blacking out would have caused far more long-lasting devastation and chaos than is portrayed here.
Originally based on a novel, I would definitely recommend watching this TV adaptation. The makers certainly have a good track record of sci-fi and fantasy. Just remember - you're not Lost when you know the future.