It actually feels a lot better to me; I haven't done my patented pull away test in a Honda S500 at Eiger yet, but for the Esprit V8, it's got great progression (admittedly right near the top of the travel, like Live For Speed) and you can really drag the clutch if you want to (although it doesn't appear to incur any penalty, e.g. heating or wear.) Racing clutches might be different, and the low-speed and general driveline physics are still iffy, as expected.
The problem is that you're not pushing the clutch in fully, releasing the throttle to less than 10% and then selecting the gear whilst both of those conditions are satisfied. I would rather the throttle monitoring were removed (at least optionally), but it's perfectly driveable if you pay attention. In fact I rarely fall foul of the throttle monitoring in GT5, usually only mis-shifting on heel and toe, which I do in all games to about the same extent (except in those that don't require the clutch, like GTR Evolution).
As has been stated many times, the real problem is the way missed shifts are handled - specifically, you're forced to deselect the gear (put the stick in neutral) and then attempt to re-select the gear with the clutch in and throttle off. Of course, you're more likely to get it wrong again, and then frustration kicks in and you do it again...