The libgles1-sgx-img package blocks the OTA upgrade via the Application Manager, but I was able todo the upgrade via apt-get with no apparent problems. I ran apt-get update, apt-get upgrade, and apt-get install libgles1-sgx-img which actually ran the bulk of the update. App Manager and Settings->About Product say I'm running PR 1.3 and I'm having no problems as of yet (and can play Tuxrace, etc. fine).