Me, I don't trust it. Too much like an inaccurate test stips. And me personally, I would fork out the $30+ for the kit. For one, Ammonia Alert only lets you know about ammonia, just one part of the cycle, it does not show you nitrites, another very important part of the cycle.
Second, approximate values are useless IMO, I'd much rather know the exact measurement than some wild guess.
Third, I need that PH and Nitrate test so I can see if my tank is running out of nitrates or what the CO2 level of my tank is.
Fourth, You only need to test everyday to make sure your cycle is going, after that, once a week or once a month. I never test NH3 (or NH4) or N02, but I do have it in case I suspect something.
Fifth, Take that attitude to the reefers and I'm sure you would get flamed, or at least laughed at. For Reefers, at Master Test Kit is an absolute MUST, One dead fish could kill off a couple hundred dollars worth of corals. lemme see here, am I gonna trust $300 worth of coral to a 5 buck product that may or may not work, or am I gonna invest in a $30 kit that I can trust. Meh, pretty obvious to me.
Skimping on test equipment is like skimping on a PSU for a computer, if trust a $10 Power Supply on $500 worth of parts, your crazy.