I have run several comparisons between 5.2 and 4.5. The 5.2 output is now much sharper than
before though it still seems slightly less sharp than the same raw files processed in 4.5. Perhaps some of this is due to somewhat smoother raw conversion.

What has not changed is that shadow detail rendered in 5.2 is less open than the same
images processed in 4.5. Shadow areas that contain plenty of detail in 4.5 contain
somewhat less detail in 5.2.

Overall, the images that I processed again in 5.2 when uploaded into iPhoto and viewed
back and forth and examined for detail and overall pleasingness- none of the 5.2 images
were more enjoyable to view on a 23" Macintosh LCD display when compared to their 4.5 duplicates.

I expect that DXO will continue to fine tune this product. The results are good enough that I think it's worth getting this especially if you have one of the newer cameras that are not covered in 4.5.