"My son (2) inherited a Duplo train from 2005 (#3771: Train Starter Set) as well as lots of track. For his birthday, we decided to get him a second train so he could combine the old set with the new one and have a large loop. Fortunately, although the track color was changed in the last 15 years, the tracks themselves are 100% compatible!
He's already figured out how to make the new train go (turning it on with the button on the bottom and pushing it) and loves putting action bricks on the track. However, we had to hide the red action brick because it makes the train stop and that just frustrates him. We do wish that set 10882 with extra track came with literally ANY OTHER COLOR action brick than red. It would be nice to be able to let him add more whistles, lights, and water stops...or even have a second green reverse direction action brick so that the train could go back and forth on a long stretch of track.
His daddy (me) likes to activate the train via the app and have a little fun making the train go back and forth, change the light colors, and toot its horn...and he doesn't know I'm doing it. Although the app (which is optional and controls the train via Bluetooth) loses connection frequently, I haven't experienced any major issues with it.
Our only real issue with the train is the battery life. His birthday was less than a month ago and we're already on our third set of 4 AA batteries! By comparison, he was given his cousin's old Duplo train from 2005 in November and that train is also on its third set of batteries in the span of more than SIX months! ...although that old train is limited to only moving forward and has no action brick response. The train will power down, but only after TWO HOURS of inactivity. That's far too long. 15 minutes would have been fine. I don't know why someone thought even 90 minutes wasn't long enough, but 2 hours was the right time to power down.
Overall, it's a good train and a lot of fun for my 2 year-old. Just be prepared to use up A LOT of batteries!"