Umberto,
I had the surgery a little over 2 years ago...believe everything you have heard. My previous surgery was on my knee, torn ACL/MCL/Meniscus, that was a slow recovery, but did not compare the shoulder.
Good News! You are probably a few years younger which will speed up the recovery & I had a lot of damage repaired. Be prepared not to use that arm for 2 months for ANYTHING & I hope you are right handed, if not learn now how to brush your teeth & wipe your A$$ with your other hand (this feels totally awkward).
Prepare by having LOTS of pillows, a VERY comfortable recliner & the one item I used the most was a travel pillow (the C shaped like used on planes) as I would put this around my arm & it kept the weight of my arm from pulling on my shoulder. When the time comes for rehab, you will barely be able to rotate your arm, but be diligent with this as it is the MOST important of all to regain mobility and the strength. It took a full year for me before confident enough in my strength to be able to ride, but hope you have a speedier recovery.
If I can answer/help with anything, let me know.
DoldGuy