EDIT: Don't see why this would work when getSelf doesn't - It's just an alias for the later.
The difference is very minor, but often missed. I suppose it can be best explained by usage within an item script, which as you know, does not work well with getself as the reference ID is temporary. However, when
This is used, it seems to ignore this check of the temporary reference and returns the object.
This can also be directly used in functions whereas
Getself needs to be stored before it can be used. The reason why it works here is probably related to the more direct way that
This works. It's one of the more arcane functions, so can't really think of any good examples at the moment.