It looks like owners of the Samsung Galaxy S3 will have to wait quite a bit longer for the Android 4.3 update. The current build of the update introduced a number of major issues causing the update to be put on hold while those issues are worked out. Supposedly, the new update causes “reduced battery life, app crashes, inconsistent Wi-Fi connections, laggy performance and even complete lockups of the device on the lockscreen that can only be solved by pulling out and reinserting the battery.” Yikes!
It's also possible the Android 4.3 update for the Galaxy Note 2 could be delayed by this as well, since both devices share some of the same internal hardware. For now the only SGS3 devices which were close to getting this update were the UK (model number GT-I9300) and South Korean (model number SHV-E210K) versions. Samsung is well aware of the problem and is working hard to fix it. We will keep you updated when more details arrive.