I loved this experience! I stayed 9 nights on the Altano, and I thoroughly enjoyed my time. It's got all of the amenities that one would need, and the boat was a great place to write.
It's not far from a metro line, so trips to Porto proper are not unfeasible. There's a grocer and self-service laundromat in very shot walking distance.
I will definitely be staying again when I'm back in Porto.