Yes, I stopped completely at the beginning of January, after about one month of playing time.
Too many things missing since past games, what is left is the same rehashed stuff, there's hardly any improvement in many areas, spoon-fed updates and seasonal events are mostly geared toward casual gamers (these people are by the way the main reason why the game has lost its magic, in my opinion).
There's really not much point for me to continue playing. It's become quickly boring over time (grind-fest), and regarding realism and accuracy (driving, settings, etc), while it does have improved over past games, it's still not enough to keep myself hooked on it like how a sim as Iracing (for example) would.
I'm glad I waited to upgrade my old force feedback wheel. GT5 has been a major disappointment for me and I don't really feel like spending more money for it at this point.
Now I'm just curious about what future updates will bring...