Former IT guy here. This is a fast reader/editor with a nice, intuitive UI. Does a wonderful job of converting/combining files of common formats to PDF, easily allows creation of new PDFs (apparently some older versions that I've seen reviewed didn't allow this(?)), and has seemingly flawless editing functionality. Also has the invaluable compression function ('Reduce file size...') that is in Acrobat Pro but missing in most other pdf editors that I've tried before settling on this one. In response to some earlier reviews below, I am using 2.5.3 on Catalina and haven't had any memory surges/issues.
I agree with one, albeit IMO minor, criticism below -- I wish I could 'Save as...' to different file formats (at least to image). Nonetheless, if you don't need OCR, then this is the best alternative to Acrobat Pro, hands down, and IMO an infinitely better deal at only USD$80 (ps., I would happily pay a bit extra for an OCR module if it were to become available..hint. hint.)