The OTA is 1.8MB in size and fixes undisclosed security issues. This isn't the 4.3.1 update we're waiting for that fixes most of the bugs.
And this is also part of the reason why OEMs don't push updates too quickly (part of, not THE reason). You likely won't see 4.3 on any non-Nexus/GPe until 4.3.1 or even 4.3.2. We're beta testers, just like the iOS beta testers testing iOS 7 right now.