I remember using a Garmin Edge 1000 to navigate through a city I don't know. I could see the street I should be on running parallel to where I was but couldn't find the correct turn to take me there.

Then the Garmin popped a big modal dialogue over the top of the map to tell me I was on the wrong street. Worse still a few spots of rain meant the screen locked and I couldn't dismiss the modal.

I came to the same conclusion, that the UI wasn't designed by some one that rode a bike.

I have to say they've got better over time though. I've had a Garmin 530 for a few years and an Epix 2 watch that I like much better. I love that the Epix can be operated with just the buttons.