We had a four month "spell" without new builds that ended in July with not-a-terrific- build, the timing of which seemed to have a whole lot to do with the rollout in Japan.
During the four months we were waiting for an update Kobo implemented ACCESS NetFront(TM) (
http://www.marketwatch.com/story/kob...ces-2012-07-02) as the EPUB 3 Standard viewer engine for the non-Adobe services they run.
At the time, Adobe continued to work on their implementation of the ePub 3 standards but in July, they had not yet released an ePub 3 compliant "backend" for ereading devices. Now they have and Kobo is making the changes necessary to work with the Adobe epub3 product.
So we had things happening at two different times, depending on format One of the goals was, I believe, what DNSB said, to have books display as closely as possible to what the publisher intended. All of this is happening to books in both formats.
There are definitely display issues that are related to choices the publisher has made which will not be overridden. I have no idea how books submitted by the publishers before epub3 changes happened behave differently than books submitted later. I would guess that there is a whole lot of variation there depending on the choices the publisher made along the way.