I found the interface easy to use with enough file conversion options available in addition to the PDF editors.

Buen servicioy desempeño

Not necessarily a rating for this add-on, but the service of their website itself is excellent. I tried many other sites for converting PDF to other formats. This is the best I ever used. It is free, and most importantly, it values quality of the conversion. No major differences that I notice after converting some PDFs to PPTs, whereas most of other websites are either charged or compromised in quality (e.g. shifting of words).