I chose an adult trike, as I have a balance problem, and can no longer ride a bike. Assembly took some time, but it arrived more assembled than most. It feels sturdy and comfortable when I ride. The hand brake and coaster brake are easy to use. It is hilly, where I live and I have no trouble slowing down or stopping, on downward slopes. (If you do live in a hilly place, having 3 speeds is a very good idea.)
I find it is easy on my back and knees and feels stable, when I ride. However, if you are used to riding a 2-wheeler, you should be aware that a trike feels surprisingly different. You may need some practice before it feels natural to ride it. (On good advice, I found an open area and rode figure-8's until I got the knack of steering it.)
It has given me back the pleasure of pedaling, which I missed very much.