I've just d/l the trial of LR4 and once again I find myself debating swapping from Ap3.
The 3 big things - for me - that Aperture lacks that LR has built-in are
- High quality NR
- Lens Correction
- Perspective Correction
Yes, I can (and do) use PS as an external editor to perform these tasks (or I could use plug-ins) but the big issue with that is that the 16-bit PSDs used are mahoosive - a 10Mpx raw generates a ~100MB PSD. Not a problem if I was running a Mac Pro with terabytes of disks, but I'm not, I'm running an old MBP with a 160GB HDD and a 320GB FW800 drive for the Masters.
I agree these are needed additions. Also needed is enough of a staff to stay on top of the new cameras and lenses that are introduced and to address these in a timely manner.