what I really HATED was the darn blade sharpener. Totally useless no matter how carefully I used it. I know how to sharpen a knife on a stone and I will tell you it doesn't work.
Not fond of the fat lines on the Omni rulers.
And I have never found any of the cute little 1/4" guides to be any use - whether the bumpers or the one which lines up the needle to the bumper or the one with the slot. But that was short money.