Excepting a couple of times where ultra tight connection and no GS agent and no MB, my 2 yrs experience with GS has been outstanding.
No wait time when calling. Flexibility to bend rules. Upgrades on reward tickets. Wife gets upgrade to F (due to MM). Never an issue finding overhead bin space. Nice bottles of wine at the holidays last year to my home. GS check-in in SFO + EWR + ORD has saved me a bunch of time.
Where UA is cheap is not allowing GS to access Polaris lounge without international J ticket. And, many times at ORD where only one of the MB is in use and the other is parked near the B to F concourse connector. (Seriously, why have 2 MB if you're not going to use BOTH of them all the time?)