It works, better for small tanks
This is an easy way to get started with adding CO2 for the smaller planted tank. Fool proof, no leaks if you give the top the extra 1/4 turn it requires. Neat and tidy, if appearances count (like at the office). Everything you need is included. Generally makes adaquate CO2 for 3 weeks, I never got 30 days personally. It may depend on your water and on whether you let it decline to absolutely zero output, I switched earler to try to maintain a more level CO2 reading. You can switch to DIY mixes when the packets run out, and those 3 packets will be enough to let you see how the plants react to added CO2.
Great for 10 gallon tanks, and smaller. Good for 20 gallon tanks if the lighting is not too much. At 30 gallons you must find some other way to add CO2.
Many will point out that you can make your own set for less cash following DIY instructions. That is true if you have most of the stuff you need laying around, but if you have to buy tubing and sealants and such, the Plant Grow system is cheaper. The diffuser is worth most of that price, it is pretty cool.
I have several, all on 10 gallon tanks. I also have DIY on a 29 gallon and pressurized CO2 on a 59 gallon.