I'm at work and haven't yet downloaded the update. But at least on paper, I'm very pleased.
Over the last 4~5 months, I kind of moved away from GT5 and onto PC sims like GTR or iRacing. And I really liked the more dedicated, hard-core nature of those simulations. So for me personally, this update seems to have delivered many of the things I was asking for:
~ A revised scale for the over-blown slipstream. BIG 👍
~ A tweak to the FFB to make it a bit more realistic
~ Full support for the G27
~ Tweaks to the physics model. GT5 felt great compared to other PS3 games. But it was decidedly lacking compared to hard-core PC sims.
~ FFWD/RRWD for replays. I used to put online events together where we'd run races up to 2 hours. Scanning the replay for 90 minutes to review an incident wasn't fun.
And now we know some more dedicated racing cars and Spa are coming. I really want to get a feel for the physics tweaks and compare it back to back. But looking at the bullet list, for me personally, they're right on target with what I wanted.