I had a blank "edit page". The upgrade itself went fine via the automatic option.
Either de-activate the plugins one by one and then refresh the page or part that's misbehaving or do it the other way round. Re-name the plug in folder via ftp if the admin is totally unusable. Remember that some plugins rely on others so it may not work straight away. Rename each plugin folder if you have to.
Remember it's your blog, your responsibility.
2.8 is very sensitive to old plugins now. That's why there are so many problems.
2.8 rocks and I'm glad I spent the time reading the help offered here.
It was a bit laborious going through all the plugins but it made me clear out my congested plugins folder :)
It is not the WP guys fault but I'm surprised that WP 2.8 breaks so easily because of old plugins.
Some love needs to flow back to the WP staff for an excellent 2.8.
Big thanks for your continued efforts.