Even though the PS3 controllers have no rumble i haven't missed it so much yet (and with news of a rumble controller coming out in the near future im not worried).
The battery life isn't as short as niftyuk makes it sound. Unless you plan to play the ps3 for 8 hours flat out you should be fine.
As for the six-axis it works suprisingly well in supporting games.
This is deffinatly the lightest controller i have ever used and play.com has the best price.