I just got my Maxxum 7d. I bought it because I already own several lenses for my film Maxxum. I've been shooting pictures this weekend, playing with settings, etc.
I have a Sigma 28-135 lens, and all the indoor pictures I shoot with it are too dark - waaaay underexposed. I am using the built-in flash only, because I haven't bought an additional flash yet.
I also have a Sigma 70-210 lens, and it is making great pictures with the built in flash.
I've read complaints from others about underexposure, but it seems to me that it's the lens, not the camera, since the other lens works fine.