Beta 5 ?? I've just spent the weekend trying it out. All rather underwhelming for me.
The positive notes;
The new healing brush might be useful occasionally. The auto detect function is a joke, but after some intervention it works well enough to be useful.
Responsiveness in the develop module is improved, a little bit.
Auto levelling ? a hit rate of about 5% here, so not a lot of use. I thought the new grid overlay would be useful when levelling images, but it disappears in the crop/rotate window just when you need it, so a fail there.
Auto perspective correct ? A slightly better hit rate, but it doesn't seem to really be that more useful than just using the manual controls.
And that seems to be the best to be said of it.
Radial filter ? just a gimmick I won't use.
Improvements in the book module ? not much at all, Blurb's Booksmart still beats it into the corner and is free.
Hopefully something will turn up in the final release to make it as compelling an upgrade as in the past, but it's not looking worth much to me at the moment.