Unlike many competing products the Autosafe uses a high security lock cylinder, making it much harder to defeat than combination lock or radial (circular key) devices (Google "kensington lock defeat" for details, but note that the vulnerability is NOT limited to Kensington products but to the type of lock used).
The locking mechanism on the Autosafe also adjusts to different depths of laptop lock slot, which helps compatibility. The security cable is also substantially thicker than many competing products, and comes with a velcro strap to keep it coiled when not in use. The key is "captive" when the lock is unlocked which helps prevent its loss.
There are only a couple of minor issues. The first is that the lock itself is quite large, making it impractical for "skinny" laptops and netbooks. The second is that fitting and removing is a bit fiddly and takes some getting used to.
Like all products that use a locking slot, the security offered is only as good as the slot in the laptop -- this is obviously not a vendor-specific issue though.
As far as laptop locks go, you can't go far wrong with this device.