I'll start by saying that my seven year old son and I really love this train....now. Assembly was a pain and there was one vital piece of track (the switch track) which was missing from the box and was hugely disappointing. All set to return it to Amazon when I was able to find the piece at a local hobby shop. The power-loc track is not as easy to snap together as they describe it. Did I mention it was a pain? Although the track "snaps" together it is still a bit delicate because the small metal connectors can easily bend if mishandled. I'm baffled that the manufacturer says you can hang the track on the wall for storage because I think it would break after the first or second time. We have it laid out on plywood and it is a perfect sturdy base. All in all it's a great starter train and if you treat it with TLC I think you could really really enjoy it. I am looking forward to working with my son to build a nice town and landscape around it.
In terms of age...I would not recommend it for anyone under 7. The wheels on the train are very small and you have to use the re-railer piece quite often but once you master that it's no problem at all. I can see where a younger child could be very frustrated and honestly it's much more of a starter hobby train than a "play and put it away" train. That said, I like this set because it has a double oval track with an elevated bridge - much cooler than just a single oval. The working railroad crossing signals are awesome. It's a great little set and a heck of a lot less expensive than the $250 Polar Express! All in all - I recommend it and a little dose of patience goes a long way.