Well, it is certainly true that Ravenclaw values intelligence, but it far more important to WANT to learn than to just know a lot of information. Our house accepts students who are curious about the world and seek out opportunities to learn more about it. Ravenclaws are creative and independent individuals too, and we encourage students to be themselves, even when that means being a bit different from the rest of the crowd.
Getting good grades certainly isn't a prerequisite to being a Ravenclaw, although many members of our house are at the top of their classes. Some students are so creative and intelligent that they just don't learn or work in the same ways other students do. That can mean that they don't get the marks they might otherwise receive in their courses. Other students might simply excel at subjects outside of the normal school curriculum.
The sorting hat does not see your transcript when it chooses your house. It looks for students who are eager to learn and creative in their approach to interesting problems. Preference is important too, as I found out first hand. In many cases, the house you would choose for yourself is the one that is right for you. If you value intelligence, wisdom, and creative thought very highly, then you are probably true Ravenclaw.