Not always. They were the first in the U.S. to release 5.0 for the Galaxy S5, and they were one of the first in the world to release 4.4.4 for the S5. They're far from the best, but they are getting better.
Hopefully the Note 3 (along with the Note 4) on Verizon will see its update soon.
I updated mine to Lollipop (had to use 4G in order to recognize it). It started out nice, but after a couple of charges my battery life is almost half of what it used to be. Then after a reboot and I go to access my app list it will take up to 10 seconds before I see my list of apps. I may just take VZW up on the Edge Up to S6!
Been very happy the upgrade. I have not seen my phone out of 4g since the update. The real test will be my summer place that always had poor cell coverage with VZ. Also fixed is an email "load details" spinning issue, this would fail in both wifi and cellular mode. Phone seem to be more responsive, can go a full day on a battery charge except when using Waze. Waze has been always a battery user. At least in a car you can plug in.