If you haven't done so, please read the Overview first.
Some SVG renders, notable Opera, do not support center-aligned text. Since
this is used to render node labels, these will appear off-center. Likewise,
Opera 8.02 does not support
tspan at all. This means multi-line
labels will be missing.
Also some SVG renderers (Opera 8.5, possible 9.0, Konqueror 3.5) ignore styles set via CSS classes. This might result in wrong styles, colors or font sizes.
There is nothing that can be done about except for SVG renderes finally supporting the full spec instead of some random subset.
Otherwise, the SVG output is mainly complete. If you notice any feature missing or not working, please open a bug report.
See also the F.A.Q.
Here are a few examples on what you can do with SVG: