I thought this would be a good toy for my son's 3rd birthday and boy was it a good choice! We also got the panels set and magnext extras (tip: don't by the magnext to use with geomag. Its not that compatible as the ball bearings are different sizes)
Geomag is a toy for 2 up but i guess due to the ball bearings, 3 is safer but my 2 yr old nephew has had loads of fun sticking the rod magnets together and looking on in wonder. My 3 and 5 yr olds have greated structures, pictures, stuck it on the fridge etc etc and enjoyed every minute. You can easily pack it in a 'bag of tricks' to take out and keep kids occupied....And mum and dad have had sooooo much fun creating stuff too thats it really is fun fo the whole family.
I would suggest a big set or a few sets to make it worth it though as its no fun the whole family fighting for more :)