Cut the Rope: Experiments is truly the best physics-based app currently available on the play store. Its high level of polish, interesting puzzles, and amazing physics make for a delectable game that anyone can and should experience.
Ironically, I have enjoyed playing Cut the Rope: Experiments much more than its predecessor for the reason that it de-emphasises the use of ropes in favour of mechanical devices that work really well. Most levels do not even have ropes, making for a much satisfying experience.
I really do wish that more developers took a cue from ZeptoLab instead of releasing buggy, unpolished apps. This, ladies and gentleman, is how you make an app.