Agreed, the built in flip-up loupe is the way to go. I always use it. Make sure it and the screen are clean, otherwise that might be causing it to appear somewhat dim. Like fhovie said, when you use this your head blocks out the sunlight pretty good. Although sometimes, when the light is coming in from the side, some sunlight can sneak through the bottom of the finder (my finder, at least). This problem is easily solved by blocking the sunlight with my hand.
I do have the metering view finder, and while it has its uses (macro shots), it's pretty large and cumbersome, and is (for me, anways) a little more difficult to focus. I'd have to try and compare it again, however, as it has been a while since I've used it.