I do the same thing. I have a temp gun for my rack. No other thermometers or hygrometers. But for newbies with single tank setups it is pretty important to have a digital probe thermometer right on the hot spot and a thermometer on the cool side as well as a hygrometer.
Sure there are better hygrometers and thermometers out there but this accurite model is fairly accurate (much more so then those round dial things) and much more affordable then digital thermometers and hygrometers from the pet store.
Sure you could spring for a $50 weather station, but that isn't very practical for most new keepers. And by that time they should already have a reliable thermostat.