PERFECT
Easy check-in instructions which made checking in effortless although Carlos was on holidays himself..
Clean and wonderful apartment, just 5 minutes walk to the river and Casco Viejo (Old Town), public transport is also very close but we never used the bus - once, we hopped on the metro to go to the coast and once we went to Artxanda by funicular, but apart from that, you can walk everywhere.. in our opinion, there's not even a need to use the tram (we had a pregnant woman and a senior with a slightly irritated knee) ;)
And the amazing communication! Carlos always replied very soon and he also provided lots of information and material, like suggestions how to spend a 1- or 2-day stay in Bilbao, restaurant recommendations and much more!
We felt really comfortable and we never had to worry about one thing concerning the apartment!
When (not if ;) ) we come back, we will definitely try to stay at this apartment again!