One of my professors asked our class if it would be OK if he just gave everyone an A. A lot of people sounded like they approved. Then he explained that if he and the other professors just gave everyone As, that some very substandard students would graduate. When they didn't work out at companies, those companies would no longer have an interest in graduates from our school. As a result, he was one of the hardest graders I knew, but also one of the best teachers.
Depending on your program of study, to compare your school with a top school these days is probably easier than ever before. You can often go online to view a syllabus, and sometimes even a video (check out Stanford and MIT on iTunes U for various computer science classes). I do think these institutions have smarter kids and push more material and grade harder than other schools.
If you are not challenged, is it OK? Probably not. It could be you are in a program that is too easy, it could be classes are watered down with remedial material when you could be learning college material. If your school offers an honors program, that might help you play at a higher level, something you will need when you enter the work place where global competition dominates in many fields. You are paying a lot, and your degrees will need to last as long as your career.
Another factor at play might be your target grading. If you are getting 4.0, you are working harder than expected. If you are OK with getting 2.9, you might want to pour on the coal and work harder. Many companies are looking for 3.5 or 3.75 GPA, and many schools offer ways to get more than 4.0 by recording a grade of A+ or awarding points for honors classes. Don't get left behind because not only are there more points available, but there has been general grade inflation that may continue so 10 years out, your 2012 GPA of 3.5 might be lower than comparable students in 2022 that get 3.8 for the same performance.
Perhaps the work load seems light because you really love this stuff. If it seems like play, you may be spending more time with it than you think, and may have