The new long-term release features a new kernel with hardware support improvements, as well as multiple fixes and new features.
http://www.notebookcheck.net/Ubuntu-12-04-4-LTS-is-now-available-for-download.110890.0.html
I've been running kernel 3.11 on my 12.04 on my Asus N550JV laptop since the beginning - it's the only kernel that allowed me to use Optimus (Bumblebee) with nVIDIA R331 drivers. Glad to see it going mainstream!
It's great to see hardware support for Ubuntu improving with each new release. Hardware compatibility is still an issue for most distros, especially when running on mobile platforms.