I don't think I need to really tell you about Cheerios. The popular breakfast (or really anytime) food has been around for decades. Currently General Mills is running a promotion with DC comics for Justice League, surely in order to get people hyped for the movie. We've covered the boxes before, but this is honestly the first time I've seen them in stores. The box art is fun, and theres 4 mini comics you could get in each cereal.
The comic that came with the cereal is pretty good! It's the 4th in the mini series, and focuses strongly on Aquaman trying to save Earth's water supply from an Alien race that wants the water for their own planet. Through understanding and the power of the JLA, Aquaman comes up with a way to save Earth's water and to help the aliens. We also get to see Arthur and Mera's "first" meeting, when they were younger.
If I could find the other boxes I'd love to complete the mural you can create by linking the boxes together, but I'm ok with just Batman–he is my favorite superhero!