Hi Mart,
I have done this now for 2 semesters, and next semester I will drop the PDF form approach. I need students to submit a bunch of information that I use to review a number of assignment parts that I score, and the PDF form seemed to be a great answer. I designed a well laid out form, that makes it easy for students to collect the information, and that had some visual appeal as well.
After 2 semesters of improvements and thinking this through, as I mention, I will now drop the idea and use a web form approach. The reason behind the decision comes from multiple problems: first and foremost, PDF forms are really problematic for Apple OS users. The forms I created are built with Adobe Acrobat Pro 9.5.4, but some Apple OS users do not seem to be able to save the data or the radio buttons I include do not function properly. Then, many students do a bunch of different things, such as saving the file as a print-out, which locks all the information so I cannot access it without transcribing what they entered (which defeats the idea behind the form), or because of their monitor resolution settings, they can't see what they enter into the form, so without clicking on each field, they cannot tell if they entered something (or if it's still empty) or if they have made an entry mistake. This last problem I tried addressing by fixing the font size in the fields, but still they seem to miss entering the information correctly.
All in all, because of the mixed OS platforms, versions, and resolution settings, I end up with many problems. Therefore, I started to introduce to Apple users (and any PC user who also wanted to do this) a web form that I created using LimeSurvey, an open source survey environment that I also host in my domain. While the surveys you produce with LimeSurvey were not originally meant to be used as assignment forms, it works just fine. Students go to the website, enter the details, and I can either access and work with the data directly within LimeSurvey, or I can download to Excel and work from there.
This solution works best for me and has no negative impact due to OS type. Hope this is helpful to you.
-George