I normally work in Inkscape 0.46 (april 2008) on a Windows XP machine. My work is intended to be saved to a PDF and distributed in that format.
This version of Inkscape does not export all features well to a PDF, therefor, I started using a Dev version, a while back, Inkscape20607-0902010619 to be exact.
In that verion, I experienced that my drawings, when exported to PDF, were much larger and rendered terribly slow in Acrobar Reader and Foxit reader. Some drawings would take more than 10 seconds to be shown fully, while it would take less than a second when exported in Inkscape 0.46.
Therefore I switched back to 0.46, avoiding features that would not export well.
Today, I wanted to test if the current Dev version would behave any better. So I downloaded Inkscape 21345-0905140303 and "installed" it. Weird thing is, I cannot save any drawing as PDF.
Here's the steps I perform:
1) start Inkscape
2) draw a rectangle
3) open the file menu
4) select "Save as..."
5) use the Save as type pulldown to select "Portable Document Format (*.pdf)"
6) Enter a name in "File name"
7) click the Save button
8) a small dialog now shows, in which I can change some settings, like PDF version, convert text to path, rasterize filter effects, etc. I leave all as they are.
9) I click OK
10 ) I now get back in the normal screen of Inkscape. No file is written, I have searched my whole system for the file.
11) I close Inkscape
12) Inkscpae responds with an error dialog, saying:
(X) Inkscape encountered an internal error and will close now. [Close]
13) I click Close
14) Now Windows reports that in Inkscape an error occurred and needs to be closed, they offer their apologies for the inconveniences (how polite...

I have tested this with all kinds of SVG images, form real simple to real complex. I have tried all kinds of combinations in the PDF settings dialog in step 8). All with the same result: no PDF is written.
I have deleted the folder with this DEV version and downloaded it again and "installed" it again, with the same result.
Am I missing something? Am I the only one to see this with this DEV version?