I downloaded the trial version of this several weeks ago (available here) but only installed it this morning. This codec seems to perform far better than the Cyberlink PDVD7 or PDVD8 one - issues I had with video/audio sync loss and loss of sync after skipping forward or back in GB-PVR are gone and the interlacing seems very good.
It's certainly well worth trying as well if you're using an ATI card - it supports full hardware acceleration with ATI or NVidia cards and it'll be interesting to see if it's H.264 decoding works any better on systems that had issues.