This Byron figure is primarily metal, but the moving bucket is plastic - it's not flimsy though. The Caterpillar tracks are rubbery and grip most surfaces but they do tend to slip off every-now-and-then and need nudging back into place.
The truth is that the non-train Take Along characters are a bit redundant as most sets involve train track, but they are still fun to have and make the collection more interesting. If you want a non-train vehicle then I would probably recommend Bertie bus or the Fat Controller's Car, but there is something cool about the working caterpillar tracks on this digger and any child with an interest in tractors will no doubt love it.
In a nutshell: If you want to collect them all then you'll be wanting this, it is one of the more unique vehicles in the range even if it isn't the most solid.