OK - it is rather simple
Add live sand, live rock, water, plug in pump and light and it's done. How many more instructions are necessary.
Heater hasn't seemed necessary, if the room is comfortable for people, the tank seems to do ok.
Mine has been up since Feb. -- mushrooms have grown from quarter size to 4" across - scallops, feather dusters, anemones, shrimps, blennys, crabs all look like they don't mind the small space.
I get water from a local shop (at .99 a gallon I'm not dealing with mixing my own). I change a gallon of water every week on the just because basis. The chemistry checks perfect.
I have the older unit - the newer one has more light / gal and the fans. Don't know if I want one or not as this one is very quiet. My hood also does not close tight which is slightly annoying but I live with it. Put a little weight on it and it does ok.
Ballast went out sooner than I expected and hood disassembly is not a lot of fun but is doable.
I haven't set up after a recent move and bought this spur of the moment so I would have at least something to watch. Haven't regretted it.