Being married to a railway enthusiast, I've had the 'pleasure' of doing this tour twice!
To be honest, I did find it interesting - well, the first time, at least. And DH loved it.
The second time not so much. Partly because it was absolutely freezing cold that day (February) and partly because we seemed to spend far more time sitting listening to the tour guide than we did riding the train. Even DH was fed up.
I would recommend it for anyone with an interest in trains. It is certainly fun to be on a train which heads off down the siding and to the roundhouse.