I had a great stay in Valentina's apartment -- would recommend highly. We communicated well before-hand, and as I arrived Valentina met me out front and helped me to find parking.
Tip: there is a free garage just past the large grocery store (not the one right near the grocery store). Street parking at the time I arrived was limited, but we found a spot in the garage.
The apartment is just as pictured on AirBnB. Very clean and with everything I needed. Large grocery just a few hundred meters away (which was super convenient, and included a large coffee bar). Several restaurants, coffee, gelato within walking distance.
The Citta Alta is a little bit far to walk -- maybe 30 minutes to the funicular to go up. There is a bus, but I did not try that.
I did a lot of cycling, and it was pretty easy to ride out of Bergamo to get to good cycling roads.
The only minor issue was that it was a bit warm -- but it had been abnormally warm weather. There is however a large fan which worked well at night.
Valentina was an exceptional hostess, and I would stay again if I am in Bergamo.