Does anyone use these?  Are they any better than regular batteries?  Are they worth the increase in price or do they just have a good advertising campaign?

I think they are. I had one in my G3 and it gave me no issues the 2 years I had the boat. You hear good and bad things about those batteries, but more good than bad.

If you use the search function, type in Optima batteries and just go back about a year, I think you will find enough comments on this subject between then and now to give you a couple of hours of reading.