I just wanted to share some answers to one of our customers that perhaps are going and going in the RS world.
They were seen some rendering 'problems':
We have several references in the documentation about this:
HTML does not support overlapping items, and will position these items next to each other on the page. To determine the position of overlapping items, the rendering extension first considers the value of the Top element for the items, then the value of the Left element, and then the value of ZIndex
When the report server generates a report in PDF format, it uses the information stored in the font referenced by the report to create character mappings within the PDF file. If the referenced font is not installed on the report server, the resulting PDF file might not contain the correct mappings and might not display correctly when viewed. In addition, the computer that is used to view the report must also have the correct font installed. If the font is not installed, the report might not display correctly.
Differences in PDF output occur most often when the report uses Arial and it includes non-Latin characters. Before deploying the report on a production server, you should test the PDF rendering output on client computers to verify that the report is rendered correctly.
You can check Design Considerations for Report Rendering http://msdn2.microsoft.com/en-us/library/ms156268(SQL.90).aspx
for these topics or do your own rendering extension if you want more ;)
From my point of view the aproach RS takes is great, as the report is stored in a render-aware format, so you can work (or 3rd parties) develop other renders and the product team can refine and support future/current formats with no change in the arquitecture.
On the other hand we should check sometimes that there could be features that some formats does not support (something obvious but not always :))