@Sylvia: We used bull balcony for our room and balcony rental, but their bull fight tickets are very expensive so we just bought them from the arena ticket office when we arrived. After each night’s bull fight tix go on sale for the next night. You have to line up early but it’s MUCH cheaper. I suppose if you really want to be sure to get a good seat you could buy them in advance, but we sat high in the arena and could still see just fine.
As for bull balcony, they were ok. There are many comparable services and I don’t think it is necessarily the best one, but I waited too late to book so my options were limited. The balcony view was good, and the apartment was slightly better than I had expected… but keep in mind that I wasn’t expecting much to begin with! If you want something nicer or quieter I would recommend staying in the newer part of town, but if you plan to take full advantage of the fiesta (and hence won’t be in the room much anyway) then it’s fine.
@Charlie: Yes, we paid a deposit in advance too. I was also a bit skeptical so I put it on a credit card that I knew would handle any issues if they turned out to be shady… I figured the 5% credit card fee they charge would be better than letting some scammer drain my bank account… but of course everything turned out fine anyway. It was not a scam. Have fun at San Fermin!