I'm used to using tapatalk on my iPad but can't get on with it at all on my new Samsung tab. Are there any alternatives ?

Not really. Any alternative would require forums to have a plug in. Given the security and stability nightmares Tapatalk has previously had, most forums simply tolerate it and stand ready to pull the plug the next time an issue arises.

Personally from a users perspective, I really fail to understand the appeal over a web version of a site. I find it horrible to use.