hi scifi and welcome to
RP.
your image is quite restorable. here's roughly how i went:
duplicate background layer
add contrast/brightness adjustment layer
add curves adjustment layer
make new layer group of duplicate and put curves and contrast into it. (didnt have to do this since i copy merged next, but was anticipating something else)
copy merged and paste as new layer
duplicate copy merged layer.
applied 'lum frequecies' to merged
duplicated that layer
added light 'clarify'.
duplicate layer
used 'digital camera noise removal'
duplicate layer
made a selection in the sky of some of the darker areas.
added hue/sat adjustment layer to selection and lightened selection to match lighter sky
repeat the same with selection and hue/sat to reduce the rest of the dark areas.
the rest was all done on a new blank raster layer using clone (use all layers), push (use all layers), airbrush, and paintbrush. this was to get rid of some anamolies in shading, noise, add definition, reduce poor shading and other little things in the image. the whole was sort of a last stage refining.
and that was it. i rarely use 'clone' on the faces any more. the smudging tends to remove delicate features of the face.
what i did i consider to be a minimum job. some more work could be done. the sky could stand some blending work and the pants could use some more definition, but i consider this at least passable.
craig