Shakers are mods and add to the overall experience of the game. Some like them but others don't care. For me the shakers all enhance the experience similar to the sub woofer. Together the seem to enhance it even more. I like feeling the rumble when hitting the castle, the ship, the volcano erupts.

If you tried a few and don't like them then save your money. I can't imagine something in this thread all the sudden making your want a shaker.

Actually, the special glass can improve scores depending. The game becomes ultra clear and it's easier to follow the ball and see what's happening in the back of the machine. Unlikely your scores will skyrocket but it could have at least some impact depending on ambient lighting.