Sadly it does fall down in one or two areas:
- Firstly, that there is no clear evidence of how many results your search finds, as there are no page numbers.
- Secondly, there is no advanced search function, hopefully this is something they will rectify in the short-term.
- Thirdly, there is no additional information in the search results, meaning you have to click on the link to see the paper.
So on that evidence, I would use this for searching for specific PDFs that you know exist, or as a last result when searching for a topic that turns up poor results.