Great place.
Location - 3 minutes walk to Diagonal station and maybe 10 to Passeig de Gràcia from where you can take train directly to Girona and Figueres.
I found it to be very easy and convenient to get anywhere with lines 3 and 5, though Diagonal station is rather huge and you have to walk from one line to another quite a bit, but they have people movers to speed things up.
Tons of places to eat and drink around, especially brew pubs. I recommend Hoppositte, and there is also a great dedicated seafood restaurant just a few blocks away. There is a supposedly good hamburger restaurant literally (not figuratively) next door, but I'm a vegetarian so can't vouch for it. Looks classy though.
A few blocks from La Rambla, yet not really a touristy area. Neighbourhood is very lively and very safe.
Apartment - clean, good size. everything works perfectly. My only complaint is that a bed while large is actually two mattresses put together, so they tend to shift during the night. The mattresses themselves are fine. Also sink is a bit small and right in the corner, but I found it to be perfectly usable. There are no windows facing outside, but I found it to be actually better when trying to sleep with a jet lag. You can hear the elevator a bit, but it didn't bother me as I woke up too early every morning.
Apartment was warm and heating/AC system works great (there is a remote).
Water in the shower warms up almost instantaneously.
Yvonne's communication was perfect and very timely.
Jessica met me at the door as promised, showed me around and gave me the keys. Even though I don't speak Spanish or Catalan, I was able to understand everything. I speak French a bit and there are enough similarities in all Romance languages, plus I've picked up a bit o Spanish living in California :)
All the instructions are provided in English, so no worries.
Would absolutely recommend Yvonne's place.