Haswell was expected to be anywhere between 5-15% faster. Some preliminary reports suggest
it's very much faster in regard to audio, but we don't know for sure yet, and there are
heat issues that need to be sorted out.
Intel has now announced
that Haswell will be officially unveiled on June 3. I don't know if that's also the date
they become available for sale. The quad-cores should be available first up.
you can wait 2-4 months then I would wait, but even then there's a small risk that early
boards with Haswell will have unexpected issues as happened with Sandybridge.
Peter Kaine and the other system builders on this forum might be able to tell us more
now that Intel has announced Haswell's unveiling date, but it depends on what their
non-disclosure agreements lets them say.