My only problem with the Unicode GREEK SMALL LETTER PI is that it consistently renders on the systems I've used as a square with the bottom portion cut off. This must be intentional, because I just zoomed in to this page to an absurd degree and it consistently renders that way even at 36+ pts. It makes sense to me that in day-to-day life with real Greek the simpler rendering is superior, it doesn't match the traditional mathematical rendering very well.