We purchased the Snap Circuits Jr. kit a couple months ago (Christmas present) for our 5 year old son because we thought he'd enjoy it. We underestimated how much: we thought he'd like it, but he LOVES it-- to the point of obsession. He spends hours a day building circuits and really has learned quite a bit. He expressed excitement and enthusiasm for acquiring other kits (he's built every one of the 101 projects in the SC100 kit at least a dozen times at this point...). So when it came time to acknowledge a job well done, I thought this little kit would be a nice reward (some of the snap circuits kits are very expensive; these mini kits seem quite reasonably priced). He was really excited to build a radio because some of the parts are different than what he has in the Jr kit- specifically the adjustable resistor, amplifier, and the FM receiver (plus a higher voltage (4.5v) battery, it runs on 3 AA) they may be redundant for other kits, I'm not sure.
In any case, he was very excited, and was able to assemble a working radio in a short time (I helped him the first time, but he subsequently was able to take apart and reassemble by himself no problem). He was delighted. He was really excited about the additional projects, too (there are 3 other circuits you can build from this kit) but the directions are very difficult to understand. The radio circuit is depicted pictorially (as are all 100 circuits in the SC100 kit) but for some reason, the additional projects in this kit are not pictured; there are just written directions and they are difficult to understand. My son is a very proficient reader, so that's not it (even I was having a hard time deciphering the instructions, and I have a college degree). It just seems like a couple more diagrams would make this kit a lot more user friendly.
For anyone else with kids that like this kit, check out the SC100 and 300 kits. My son can't wait to upgrade and is asking for the snap rover kit for his birthday in a few months. He's hooked. Overall from both a fun and educational perspective I've been really satisfied with these toys. As far as durability, what we have has been experiencing heavy use for a couple months and so far has held up well. There are little improvements to be made here and there (I also intend to review the SC 100) but overall I think they're great and if the enthusiasm persists, I see us buying more.