Actually it's better to collect feedback from you guys at early stages, so you can check and explain what you like and what you don't like there and think should be changed. All of this is not (only) about the bugs.
There is no point to introduce something 90% ready if then the users won't like it and then it has to completely re-done.
The idea of early preview is to get idea of the overall experience using these new options.
I.e. - you may not like the new hover icons, or you may not like how the new actions for selecting image/video source inline works ... or you may not like the tabs switching the elements/blocks etc.
We already got some really nice ideas about the new options, shared by other users:
Also you can already check many of the things like:
- new elements insert dialog / its animations / tabs
- add blocks to your page
- new insert image source / video source options
- new text edit options
- new hover colors/styles/icons