I thought the restoration was quite impressive when I saw it. I am not an art historian, of course, so I can't measure the accuracy or the quality of the restoration, but I saw it both pre and post restoration, and it was so much more bold and alive post restoration.
Which leads me to consider that even if imperfect, it is likely closer now to what Michelangelo intended than the pre-restoration version (of course, Mikey didn't want all his lovely nude classical figures to be drapped in clothes, but that' a different matter). What I mean is not the quality of the painting. Rather, it is that when it was originally painted, it would have been bright, clear and dazzling. I am sure that it transformed an otherwise dreary Middle-ages chaple into something brilliant.
And, it seems to me, being able to see the paintings clearly was at the core of that transformation.
My recollection of the pre-restoration was that it was beautiful, but dark and obviously faded. Not how the artist intended. So, hopefully, this restoration did something to bring the painting back...in color, clarity and brilliance, to the intention of the artist, and in that way, it seems to me, it is faithful to the original (even if the techniques employed and determinations of color, etc. aren't quite perfect).