Welcome John, it’s good to have you here.
I won’t go on too much about my CGM because I’ve raved about it so many times in posts but to answer your questions briefly:
I love it, have had it for 4 years and would fight to the death to keep it.
It isn’t particularly difficult to use, but takes some getting used to. You might find these posts useful:
The pros and cons of CGMS – https://www.shootuporputup.co.uk/2009/04/to-cgms-or-not-to-cgms/
What difference CGMS made to me – https://www.shootuporputup.co.uk/2010/06/what-made-the-difference/