Ours in running great it's been up since March of this year, we only have 5 pounds of live rock in it, because of how tall the lid is we've never had any problems with heat, we also use a clamp on PC
light by JBJ that seems to work great although we are going to upgrade since we've added the GSP recently. We do weekly water changes and have a small power head that we got at Doctor Foster Smith works great and a power filter an Aqua Clear that only runs with a sponge in it. We have one fish which our kids named Jet who stays in one place all the time a hole in the rock he is a barnacle blenny and is quite small. It's not hard to maintain at all and basically takes care of itself with an occasional top off which seems to be once a week. We seem to add more water to our 29 and 40 than we do the 5 can't explain that one.
We enjoy ours so much life in such a small area, we also had a small starfish that had hitchhiked on one of the rocks and has since multiplied, they are small enough for this tank and don't hurt anything, we have 5 or 6 of them now not to mention endless snails and brittle worms and featherdusters.
We figure a rough figure of a little over a hundred bucks that's not including fish, crab and corals.