There isn't a demo for this app and that's a pity because it's actually a good app. I bought it out of desperation when Apple killed the Character Viewer's "Glyph View" in Lion, so I had to run Windows XP with Parallels Desktop just to work with the standard Windows character map app.
Anyway, I found this app here does the job well, not much more but nothing less. Both regarding price and quality/UI I do recommend it over PopChar X. The developer is very responsive and it get's updated frequently. Worth its price.
However, a shame that now we have to use third party software for this. There are many people using a Mac in science, etc. who needed Glyph View to use their custom made, field specific, fonts with characters that are not there in Unicode (yes, there are characters that are not included – yet – in Unicode).