I would sign up for it if it was available up in Valencia. Last year I used the service quite a bit when I was in town (and in the area they had coverage). They had a P50/day code you text to a number as well as 1k/month (or maybe it was 1.5k). It was extremely fast but the coverage was very limited at that time. You should also note that having your phone connected to an LTE signal drains the batter very quickly.

And isn't a portable landline phone just a mobile phone with a land line number attached to it?