We upgraded a pair of 515e's last night from 7.2.2 to 22.214.171.124.
The upgrade was fine, however when we tested both L2L and Client based VPN connections we hit issues and were finally forced to roll back to 7.2.2 due to time constraints.
Our problem with the VPN was 1st noticed with a L2L tunnel, trying to ping a device on the LAN from central site, the PIX logging produced a message that said there was no port map translation group for the returning traffic, ie echo reply. Interestingly telnet worked from central site to remote, but not ping. We also found that any connectivity created from the remote site also had the same issue, likewise for the client based VPN's. We never changed the configuration of the PIX, and a NAT 0 was setup from high to low. I dont believe there should have been any other features added to the code, just bug fixes.
We did try several other things to try and get it to work, including sysopt permit vpn, reboot, nat 0 on outside interface, etc.