It likely wasn't the adoption rate Google was hoping for, but it appears as though Jelly Bean seems to have finally been taken on by the majority of Android users. While it has been almost a year and a half, and it is marginally more than half of Android users, those upgrading to Jelly Bean 4.2 have increased steadily over the last few months.
Google recently published its October operating system distribution numbers straight from its OS dashboard, and we can see that 52.1% of Android owners have moved up to Jelly Bean, with 26.3% still on Gingerbread and nearly 20% on Ice Cream Sandwich.
Diving in deeper, we can see that most of the Jelly Bean users are still on the older version 4.1 at 37.3%, with 14.8% having moved up to 4.2 or higher.
Even with adoption to Jelly Bean starting to reach a significant number and upgrades to 4.2 on the rise, it all just seems to-little-to-late with Google's new Android OS already starting to reach the public. Android 4.4 Kit Kat is designed to support as many devices as possible, so its likely Jelly Bean won't remain at the top of the list for very long.