Yeah - I was definitely impressed with how quickly the thing turned over the first time with the Optima.

They can deliver a LOT more current than any traditional battery.

Oh, an FYI... you'll hear some people call them gel cells. They aren't.
Optimas are lead acid batteries with the same chemistry as any other lead acid battery - they just have a different structure inside that allows them to use softer more pure lead rather than having to put in a bunch of other crap that will make the lead strong enough to support its own weight. It looks like a swiss cake roll, actually... or, rather, 6 swiss cake rolls connected together. The extra purity of the lead provides higher current capability.