Usually, users are more appreciative towards user interface improvements, probably due to their immediately visible and perceivable aspects, nevertheless, under-the-hood changes are always a proper addition to a fancy interface, enriching its beauty, speed, ease of use, etc.
Opera 12.01 has just been released, mainly as a bug fixes version, bringing numerous security and stability enhancements, that are to take the recently introduced features and eyecandy polish to a stronger, solid web-browser.