Like Dima, I'm currently using the packaging, so it should work.
The reasoning for waiting till after the freeze is there's a number of things we need to sort out with upstream, and given their responsiveness trying to do this before the freeze seemed impractical. The issues as I see it are:
1. The matlab/octave interface seems poorly supported (upstream may or may not drop it entirely), it uses a custom build script written in matlab (which requires modification to work with octave), which means we don't get multiarch easily. We could have dropped the interface, but it currently works (afaik), and the real solution (split it out and make it a proper octave package on octave-forge) would be time consuming and probably wouldn't happen before the freeze.
2. Upstream has broken the ABI in every release without bumping the so number (this is the most time consuming part of packaging sundials), and don't seem to think/be aware that this is a problem. My packaging went ahead and did its own thing (given upstream's response), but that's not really a viable strategy in the long term. I also raised the ABI breaks on Fedora's bugtracker, but nothing's come of that.
3. There are no real tests, there's some examples, we'd need to ask upstream for tests (if they have any).