Fish Tales: Difficult because its almost perfect but if pushed I'd have to say the lack of a plunger or skill shot when launching a ball. I have yet to perfect the video mode but I regularly get the EB and at least 18/20.
LOTR: I will say that it is very well made game but I found that although very deep it lacked width. To explain, I always felt like I was setting off on a path of ticking off tasks in a certain order and never felt like I was making live tactical gameplay decisions, instead slogging away at a very long and winding path. POTD is also obviously a bit dull as is "Get hold of yourself!" every few minutes. The balls tended to get stuck quite a lot too. I'll stop there but it is a quite flawed game IMO although it also has a lot going for it.
Doctor Who: Maybe just my particular machine but I found hitting the orbit would often lead to bouncing off a bumper and sending it back SDTM. The game is too tied into the video mode and of course that pesky time expander is constantly needing fixing.