Choice of skimmer is heavily dependant on your application needs. Having owned both brands, I will confidently say both are effective skimmers.
I stuck with my Euroreef for three main reasons: it was quieter, more energy efficient, and easier to service then the Bullet. Jeremy is spot on with the impellar issue; Euroreef impellers will break because of swelling if you turn them on/off too often. Not a design issue with the skimmer, per se, but rather the pump provided.
Again, both are great skimmers. It just depends on what you're looking for beyond sheer skimming capabilities (which both possess in spades).