My friend has been banging on about it for ages every time we go out for a drink and he finally wrote me a DVD with the first 10 episodes on so I'm watching them through.
The concept is really good for a start and everything to do with the investigation side of what the Flashforward was/is has me hooked.
There are a lot of family scenes that drag on a lot though and I find the lead guy to be rather lacking in charisma. Sonya Walger always irks me as well for some reason. John Cho is in the show though and he's awesome so that helps.
I'm liking it enough to keep watching so far (first three episodes) but final judgement is still out.