I have had some success with pdftohtml in the past.

It wasn't easy though. The tool has 2 major modes: I can't remember exactly what the problem was with the html mode, but I ended up not using it at all. I used the xml mode, with a LOT of post processing (in Perl).

For starters the XML was not valid (i, b, u and a tags where not properly nested), so I had to disentangle them. Then what you get is a bunch of strings with their position on the page. From there I had to order them, merge them to create lines (sub/super scripts needed to be handled of course), and then create paragraphs... fun!

That was with version 0.36, the one that seems to come with most Linux distributions (it was released in 2002). Sourceforge has some more recent ("experimental") versions. I tried 0.40a, which produced a wildly different output, at least in xml mode, and gave up. The problem with version 0.36 is that it has problems with some recent pdf (version 1.6).

Overall it was quite painful, but in the end I managed to extract some information from the files.

Obbly enough I am currently using pdftotext for an other project, and it seems to be doing quite well, even though of course the output is simpler than what pdftohtml produces. I haven't noticed it dropping letters so far.