It's durable, keeps good time, battery lasts 7-10 years, clear display, thin and light. It's incredible value for $15-25. Deserves to be as popular as it is.

The only real drawback is the terrible backlight which is fixed by the F-105W which has a soft blue EL backlight <3. Much preferable to the 91 IMO. Functionally both watches are the same.

I have probably ten- not precisely the same model- in the past thirty years. Most common failure is strap breaks after taking the watch off for swimming every other day. Second most failure is to shatter a corner due sports- hit my wrist on something. Third is a humidity leak when I visit the US South in the summer.