Hi. I don't know Eureka but I do know Arcata, which is super close (appx 10 miles), super cute, and a college town. Remember that you don't have to live in Eureka!
It is very foggy, rainy, and cold up in that area but it is gorgeous with all the redwoods. Just like FullGlass said, Eureka is like any town: Good and bad areas. You can get a better idea after you visit and talk to more people. Good luck!