It probably doesn't deserve the bashing it gets... in fact, it was pretty dead on with the first landfall in FL. Models continue to shift west... I think you are right with a shift west at 5pm from NHC.
The weakness is very small (NO to Pensacola area)...
http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8dlm3.html
So far she just doesn't seem to want to turn north at all.
http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?wv_east_enhanced+12
It's pretty clear why the NHC thinks Katrina will move north and why Texas is in no danger.