I followed the IP fast ring on my 920 and I saw lots of different results depending on Choices I made. There were also issies With certain apps, like the cool Lock screen app I dont remember the name of. Also, following the update path cuold have some unfavourable results. And the just resetting the phone could have different effects on the same build than doing a full restore of WP8.1 and starting directly on the lates build. Also, choosing not to start from existing backup worked Wonders on the latest build I have on my test 920. Its super fluid, snappy and fast. And I have not updated in the last month.
Being part of the IP program is dealing With these issues and Reporting to MS, not making threads online about the problems you have. We can all do that when the "final" release is ready.
And, if you complain about lack of apps, do you think ranting online will make ppl buy Windows Phones? To bad if they deside not to because they read (bad things) about the OS that turns out not to be valid by the time the OS releases to the Public.
Also, not all Phones are getting it at the same time. It could be they are aware of the remaining issues on some of the models.
Also, Close to release does not translate to no updates to the final build.