Just recently bought the Glass Master Pro & love it.
No more contortion acts trying to clean my front & rear screens.
I did find however that there is a slight learning curve...
Felt totally foreign to me at first, can't even explain it, maybe using different muscles, etc?
Also found that on a screen that has been quite neglected it was quicker to give it one GOOD clean the old fashioned way then use the tool as a maintenance type of item...
Just can't (or I didn't) get the weight or pressure on the tool that you can by hand