We had a small window of opportunity to release a new sdk version and opted to release 2.0rc2 as-is so customers could begin using it- even though some things (new styling, etc) may not be totally done. It looks like there are some issues with tab panels from your example above. We aren't really using these in the product currently, so that makes sense. Are there other components which are especially bad?
We may be able to offer some small css fixes or ext overrides to get things to look more consistent...