I'm older than the given age range and I still loved playing this game! I especially like that these are all real species of plants, stylized into lovable characters. Each plant has its own unique appearance and personality. The game only has a few minor issues or things that could be improved.
The main problem is that it's rather short, lacking anything to do after you collect every plant. It could definitely use something to do afterwards. I read some of the other reviews and someone suggested adding a shop portion where people would request plant hybrids and you would have to fill out the orders. I think this edition be a really fun solution to the shortness issues! It would be especially fun if it didn't show what plants you needed, so you would have to put thought into what you needed to mix.
Speaking of the plant hybrids, I really wish there were a way to catalogue your creations. As a kid I loved drawing monsters and coming up with funky names for them, even now I still do. I'm sure there are other people out there who love to do that, too.
I also really wish this were more of a "find it out yourself" game. All the plants have little notes next to them showing what they like as soon as you unlock them. It would have been way more fun to find that out myself. I found myself doing my best to ignore those little notes so that I could enjoy playing around with the plant and figuring out what it liked on my own.
Something that also would have been more fun is if the game had more emphasis on growing the plants. You put sun on a plant, it spits out a seed, the seed cracks open into a fully grown plant creature. I wish the seed would become a cute little sprout in a pot and you had to water it, put the sun lamp on it or feed it to grow it to the next stage, and the next stage, and so on until it's a full grown, wacky looking plant monster. When the game said you "evolved" the plants, I thought something like this is was what it meant. To be honest, nothing in the game screams evolution to me. None of the plants evolve into another version, so I'm not sure if I'm missing something or if my definition of evolution is different than the developer's.
So, the game is really fun, but it's super short, lacks much of an end-game and could benefit from some content editions. I'll give it four out of five for now, but if the developers update it with some more end-game content and a hybrid plant catalog, then I'll reevaluate it and I bet it'd be five stars!