I'm loving Lightroom 5. Each new release adds new features that increase Lightroom's ability as a stand alone product. This time around we got a properly functional healing brush which, for smaller items, saves a trip to a separate editor. But perhaps the best addition is the new radial filter. The radial filter adds all the controls of the gradient filer but in a circular or elliptical shape - this is so flexible and substitutes for the sluggardly Adjustment Brush in many situations.
The Adjustment Brush aside, there have been all round performance improvements in LR5 which are very welcome. The Adjustment Brush however, is still capable of bringing a quad core processor to its knees. Here's a tip - if you have to make extensive use of the adjustment brush then, once you have finished, export the picture to a TIF file and reimport it to Lightroom, then you can carry on working on the TIF file without all the brush history steps bogging the system down.
This picture uses the new Radial filter to darken everything except the flower and underside of the stem. All processing done in Lightroom 5: