Eureka is never going to be remembered as a "classic" or "groundbreaking" SF show. It could, however, be remembered as one of the more charming and offbeat SF shows to come along in a while. It is a bit slippery to classify, but my best description of "Eureka" is kind of "Northern Exposure" for SF fans.
"Eureka" has thus far been family-friendly light adventure with its humor coming from the quirky nature of the brilliant scientist locals and the "fish out of water" experiences of new sheriff Jack Carter and his teenage daughter, Zoe.
Those tuning in to see traditional SF--where speculative fiction and profound "what if" moments rule the course of the show--will be disappointed. There won't be many serious examinations of the impact of new technologies here. The tech is secondary, actually tertiary. The odd characters are the focus of the show. Second to that is the weekly mystery. "How can the tech-ignorant sheriff learn to work with the ample supply of local geniuses to save the day?" Finally, comes the tech. And when tech is dealt with, it reminds me of vintage Geordi la Forge technobabble. I swear that someone was going to "reverse the flow of the graviton emitters." So, "Eureka" is not great SF. Nor is it great drama. Nor is it side-splitting comedy. It is instead an amiable and lightweight mix of the three. Eureka is not at all unlike "Northern Exposure's" Cicely, Alaska. It is a very pleasant place to visit once a week.