My experiences have been positive with BetJamaica, however, after using thier cousin Olympic, if I had a choice as to which one I'd go to first I'd go with Oly no questions asked.
Oly breaks the games down thoroughly into team totals, quarters, and has totals on almost all games on the board. As a bettor you don't have to wager on quarters or team totals but it is to your advantage to have them available.
BJ has totals on televised games only.
They don't have second halves on some of the late games.
They don't have overnight lines.
Oly has halftime lines up sometimes a few minutes before the half, BJ waits till halftime and therefore some of the value to the bettor is lost.
Oly has totals up early, BJ has them up the day of the event in a lot of cases, so if the line moved against you the day before, you are stuck with betting what it is now as compared to what you could have got it for a day or two or three days sooner.
BJ is a decent book to turn to if you're the average bettor looking to bet a side on an average football game, but if you're into totals and halftime wagering I'd go with Oly. There is a very big gap between these cousins, they would be up there with Oly if they could narrow the gap and offer a more complete package in a more timely matter.