F ound this manual on the internet on how to get the Google version of Android 4.3 (Jelly Bean) on your Galaxy S4. Tried it out and this is my conclusion:

Pros

• Blazing fast (including camera)
• no bloatware installed
• Looks better than Samsung Stock ROM (matter of taste tough)

Cons

• Camera takes pictures only in 4:3
• Some really cool features like AirView are not available in the Google version
• Flashing a custom ROM will void your warranty (see this post for details)

Bottom line: Went back to original Samsung Android 4.2.2, since an upgrade to 4.3 will be coming soon anyway (and looks promising, according to this post).