The Petzl Calidris is among the most streamlined big wall models in our selection. It is just about tied with the Black Diamond Big Gun for lightest big wall harness. We found it not as comfortable as the Big Gun but much more breatheable and suitable for free climbing. Get the Big Gun if you plan to do a bunch of walls but the Calidris if you also want to use this harness as a comfy trad cragging harness.
Compared to the Metolius Safe Tech Waldo, it is not nearly as comfortable but much lighter. We prefer the Waldo because of its comfort, better and stronger gear loops, and the fact it comes with two belay loops. If you are only going to do a few walls, we would probably recommend the Petzl Corax, which is only $65 and much more versatile. The Corax is not as comfy but it is reasonably comfortable overall.
We give the Calidris our big wall harness Best Buy award because it is tied for least expensive harness with the Black Diamond Big Gun. However, unlike the Big Gun it also makes a great free climbing and all-around trad climbing harness. You are likely to get a lot of use out of it when not on a big wall.