I upgraded my LR 4.4 to Lightroom 5 yesterday. I do not see transition from version 4 to version 5 to be any dramatic change but there is one fantastic tool included in the newest version. This tool is Radial Gradient Tool. With it you can easily select round or oval area which you mask (protect) from or select for the adjustments. You have all the adjustment palette you are used to have e.g. for Adjustment Brush. This new tool is so much easier and faster to use in many instances as compared to Adjustment Brush or standard Gradient Filter. It is possible to invert your selection so that the adjustments are affecting the background area or the selected area. You can for example very easily protect the area you want and decrease the exposure in the background to emphasize your main subject. As an improvement of its present status I would like to see a possibility to “copy” the selected area and after that invert the selection for that same area. Then it would be possible to do fast adjustments both to the background and the selected area without making the selection again.
In the shot below is a rusty chain. I selected the chain by making an oval selection with Radial Gradient Tool. After the selection I inverted the mask so that my adjustments will affect the chain, not the background. I did only few subtle adjustments. First of all I made the chain more “warm” by adjusting WB just a little bit. Then I increased exposure, clarity, and sharpness very moderately. I feel subtle changes are the key here. In that way you will emphasize your main subject nicely without ruining your shot.