Are Sientra implants better than other breast implants?

I've been hearing a lot about Sientra breast implants lately with a lot of people saying they are better than Mentor and the other competition. Since I'm planning on getting breast implants sometime soon, I'd like to know if this is actually true and if so, if the Sientra implants are more expensive and/or worth the extra expense if they are. Thx.