Be aware that (lack of) water pressure can be an issue, unless you stack your barrel very high (like directly under your second story gutter). You'll either need to just use the barrel to fill watering cans for hand watering, or get a pump. We had a "professional" install ours (and I do mean those quotes ), and it was supposed to be integrated into our irrigation system, but it turned out that wasn't possible because of the water pressure, so we wound up paying for a barrel that we rarely use, and just letting the grass die.

You'll also want an inline filter to screen out algae and debris that can clog your hose. Those can be hard to find in some areas, but irrigation contractors should have them if your home improvement stores don't.