This is the website for Tapastic
I did a lot of research on them, and I found the lack of objective 3rd party information rather alarming. It seems like it will be a great deal for comic creators, until the money runs out. So, if you do webcomics and are willing to market yourselves aggressively, do it. But be sure to be an early adopter, if you want to get the big cash bonuses, which last until the end of April.
Personally, I feel really sorry for the investors who put $750K in seed money for this project. As far as I can tell, there doesn't seem to be anything special in terms of monetizing the site, and I haven't gotten the impression that anyone there really knows what will be sustaining the site in the long-term. As of yet, their claims of reaching out to a more mainstream market beyond the webcomic niche do not seem to be materializing. Instead the majority of their promotional efforts seem to be focused on the efforts of the artists to drive traffic towards the site.
I am an outsider, so I don't know all the inner details of Tapastic, but as someone who made money on webcomics ancilliaries (until I stopped touring -- which pretty much killed the gravy train,) this just doesn't seem sustainable. If someone from Tapas Media is willing to comment, I'd really like some convincing that this isn't going to be the Boo.com of webcomics.