I have a Garmin 450 on the FJR and a TomTom Rider on my Tenere. The Garmin interface is better to be sure. More intuitive software and more options for data display. I've heard that the Garmin map data base is more detailed, but I've not noticed any issues with the TomTom. If you want a basic device that offers basic functions, then the TomTom will do the job. It is not the GPS you want if you are a serious and competitive LD rider. The TomTom Rider does have a computer based trip planning program, but I have not tried to use it.
For the average rider the TomTom is a great return on investment. At $210 compared to $600-800 you have little to lose.