Besides simplified installs to begin with, I like the idea of having a fairly rigid reservoir. I am going to dig one up next week that I installed five years ago. Over the past two years the volume of water it will hold has decreased due to the ground around it pushing in. The pump got something stuck in it and I could not even get the pump out. The ground at the top of the reservoir had pushed in, almost to the the concrete blocks that hold the ceramic fountain.
Bottom line, a couple very heavy rains and the customer not keeping the water level up high enough contributed to it. You can't control that. If it had been a rigid basin, it would not happen.