I've spent last few hours watching the last episodes of Caprica as they decided to show them all at once. I suppose it's good they were shown at all as the rating were pretty bad for the series. In fact it was easier for me to enjoy the action watched like this. It was after all one continuous story.
I think the problem with Caprica was that one - people knew how this ends, knew it ends badly and it is hard to get attached to characters we know are doomed. This already happened and all their struggles cannot change anything. Two - the most likable and awesome characters were those who, as was suggested, were to become cyclons. The cylons who were to genocide the Colonies and who were the bad guys of BSG. The show made one root for bad guys. I loved it but I can get why it could turn people off. This and the fact that all the humans were so damn despicable for most of the time.
I think that, and the lack of space battles, were the main causes leading to people loosing interest. There were of course some other things that bothered me more but from experience I know these are not the things that get shows canceled (quite the opposite actually). I wrote about the before so all I wanted to say is too bad as it just got better with that.
There were some things that I really liked in those episodes.( Caprica - rest of 1.5 - SPOILERS )
I liked those episodes. The ending was rushed but given the circumstances that was unavoidable. I liked the series as a whole but never felt truly passionate about it. I suppose I'd have liked it better if it wasn't connected to BSG in any way.