Good code should be clean, simple and easy to understand first of all. The simpler and cleaner it is, the less the chance of bugs slipping in. Moreover, elegant code is very often the result of careful analysis of the problem, and finding an algorithm and design which simplifies the code greatly (and often speeds it up too).

Showing how clever the author is, only comes after these ;-) Performance micro-optimization (like using the bitwise operations you mention) should be used only when one can prove (with measurements) that the piece of code in question is the bottleneck.