There have been problems with the seat mount on the 1st chairs from before last year. As far as I know they've fixed all the bugs in them since then. I bought one a couple of months ago and it seems legit.
I did read a disclaimer about the thrones on the Tama site. The problems are on a certain production run and I'm sure a company like them wouldn't be making those mistakes now.
I think just about every company, especially the stuff from overseas make a product here and there that is garbage.
more info on that issue here:
http://www.tamadrum.co.jp/world/1st_chair/index.html