From my experience I can verify that it is nt much fun to use at the moment.
I built a char around it, hoping to avoid both Assassin ("stab stab stab!") and Shadowdancer ("bloody light!" *grumble*) RP while retaining a pretty useful defensive measure (especially useful if you are not minmaxed and fully stacked with epic gear and therefore suffering from mediocre AB&AC and terrible saves).
As it turned out "Hide in Shadows" is useful only in those situations where you would survive without it, too.
As I am still not fond of being forced to RP an assassin or Shadowdancer I started pondering about how to turn Hide in Shadows into something useful without making the two prestige classes obsolete. (Another solution to my "problem" would be to introduce Scout, Dark Lantern or Nightsong Infiltrator to BGTSCC - but thats another topic.
So here is my idea: how about turning "Hide in Shadows" into something like the opposite to Ranger HIPS?
Ranger HIPS is working in outdoor areas only (or in addition in natural caves, too, if you invest into the Cavestalker PrC).
So "Hide in Shadows" could - if that is scriptable - be working like "real" HIPS in urban areas and indoors, only, with the exception of natural caves.
Rogues are in their majority an urban class anyway so it would be pretty fitting from an RP point of view, too.
If not in an urban area, a house or a non-natural cave, "Hide in Shadows" would still function as before.
As it needs Rogue level 10 at least I cannot think of any serious powerlevel problems as it would essentially be a "watered down HIPS".
Thoughts?