This even works on mobile - wow. GAMs are great tools. However in my understanding they can be quite unstable when working with (subsets of) medium sized data.

This even works on mobile - wow. GAMs are great tools. However in my understanding they can be quite unstable when working with (subsets of) medium sized data. In other words: it's easy to formulate quite complex models that seem to work, but fail at prediction. So as with any complex modelling mastery is the key.