I didn't buy my Kobo Aura One for PDF reading. I was quite happy to do that on my iPad. However, I do have a number of PDF books, and out of curiosity I tried them out on the Kobo. As a standard PDF, I found it a waste of time. Converted to an epub via Calibre, it was even worse.
However, I came across a program called K2PDF
http://www.willus.com/k2pdfopt/
which does a different sort of conversion, to a resized PDF. I chose the Kobo Aura output and it is immaculate. Exactly like reading an epub, but in PDF format. This is for a book with occasional illustrations. I don't know what it would be like for more complex PDFs.