Next to worthless. Very slow. Keypad feature doesnt work. Doesnt work at all if you have two "partitions" in your system. I have one partition in my office over the garage, and a second partition controlling the house. This app only lets me control only one of these (unless I use the ridiculous virtual keypad discussed shortly), and will not show any events or any sensors that arent in the office (partition 1).
More to the point, the app makes nothing easy for you. You must use the virtual keypad, which works only intermittently---sometimes not at all (it silently ignores some, but not all, of your keystrokes, so you cant predict what its going to do. Even when it does work, it works exactly like the standard keypad, forcing you hit multiple keys to do anything. You have to enter your passcode multiple times to bypass a sensor, for example. It shouldnt make you type xxxx*2xxxx2 (13 keystrokes) to arm partition 2, there should be a single button that does that. I dont want a virtual keypad, I want an app that makes it easy to control the alarm, with single buttons that do common operations. Why perpetuate the limitations of a physical-switch-and-two-line-display, when you can provide a decent user interface? This is what happens when hardware companies write software. Its junk.
The web interface is equally awful.