I have used a number of siddurim apps for my smartphone/tablet and have found the text layout so abhorrent (nikkud floating all over the place, unprofessional kerning, ugly fonts etc.) that I've given up on a native rendered text solution.
I've also tried to find a decent pdf but can only find historically significant but difficult to read scans from archive.org or hebrewbooks.org or doc files that have been exported to pdf and suffer from the same hideousness as the native rendered text. Does anyone know of a professionally typeset pdf siddur? Vector text, bookmarks and free are preferred but not essential.