Seems like Trinisphere isn't all that popular of a card among shop players in Europe. Interesting....
Doesn't do anything unless it comes down first turn. It's also much worse on the draw. Lots of conditions. As a 4-of it would be fine because you could reasonably expect it in your opening hand often -- as is, it's not incredibly impressive.
Also, there's the big reason that it's pointless with multiple spheres in play...not to mention turn 1 trinisphere on the play gets a lot worse if you don't have a recurrable way to kill their lands (smokestack / crucible+strip lock).
TL;DR -- It's not good in MUD.