I reviewed the features of the Mio 305HC against the similar Garmin computer and in reading there would appear to be little in it.
Having used this computer the features are excellent and the display perfectly clear, it is not only a great riding companion t is proving to be a great training tool. Since Ive been rigged up to this computer my own performance has improved 10% in 2 weeks.
Because of this unit I am already enjoying my cycling much more.
Have only started using this device, but so far very impressed.