I like the look here, certainly it's not consistent with ROTJ, but it's not consistent with TPM or AOTC Sidious either. There has to be something revealed in ROTS about his "veiling" that also explains this look, me thinks.
Maybe he's somehow concealed his appearance (or non-hideousness) as Senator/Chancelor Palpatine in a way that maybe he still does to some extent in the OT.
Then again maybe it's just artistic license to make him freakin' scary for this scene. It sure looks psychotic. Love it.