Twin boys, aged 3 love these toys. We bought all three (Fire Truck, Police Car, Construction Truck). The Fire Truck and Construction Truck both convert to 3 different types of vehicles while the Police Car converts to two. My eldest, 7yo girl, also likes this toy, but the boys can't get enough. They will pull it apart, use the drill, race the cars, etc.
TLDR from my experience: Hours of fun for ages 3-7 boys and girls, more so for the 3yo boys. Be prepared to help build if you have younger kids but otherwise super easy for littles to take apart. If you buy more than one and the remote gets confused, no worries, it will eventually re-calibrate and correct. Also, it goes without saying that small pieces may be misplaced by kiddos. Return if needed was done through amazon and super easy. All in all, worth the price.
This is a great STEM toy for boys or girls. There is one base for three different trucks - cement mixer, dump truck, and a digger. My 7 year old grandson loves it. Eventually, he will likely take it apart and put it back together. I appreciate that the remote control option is quite slow and not crazy fast so that it runs into everything.