Well, I had a little go at it last night - it's a very nice progamme, it reminds me of Helicon Filter, which (free version) I also tried out for the first time within the last week.
I think I'd prefer this to Helicon Filter if just working on a very small number of images,
Some comparisions: Sagelight (SL) with Helicon Filter (HF) - Disclaimer: remember these are first impressions (please correct me if I wrong anywhere!)
~ Both are easy to use - just mess around and see what happens!
~ Both have a split pane view - original & current modification; in SL one-click shows you the original image at any time no matter the view
~ SL has the better rotate image - simply cause there is a grid overlaid - no guides in HF
~ SL has the 'Undo Brush' so you can selectively undo any of the effects
~ HF has noise reduction - cant find any in SL [I just found a 'Smooth Skin/Image' edit which = Noise Reduction,
preview of effect doesnt allow you to zoom in though, so you cant really see effect unless you apply it... - a confusing interface here with changes shown 'live', and also a 'Preview Selection' setting which has the limitation as described in strikethrough text combined with: I not sure what exactly it's previewing ]
~ HF will correct chromatic abberation (have not tried) and you can adjust for a certain amount of lens distortion or from incorrect angle of image (skew etc)
~ SL - there doesnt seem to be a way of having a folder of images visible as thumbnails | with HF you can open a folder & select images, or even batch process (for what that's worth)
~ oddly, Sagelight does not have one shortcut key - not even Ctrl+O or Ctrl+S - that would drive me crazy if I wanted to work on a lot of pics (also have to use window open dialogue to find your pics)
 added SL noise reduction [/edit]
 corrected SL noise reduction info [/edit]