We stayed at the Casa Santa Rosa for two nights - room 8. The room was located off the main garden, so we didn't have ay issues with noise. The location of the hotel wasn't truly centrally - it was a few blocks from the main drags. The trade off for walking a few extra blocks though was a nice and peaceful location.
The room itself was very spacious - big bathroom, two full beds, a sitting area, TV (with cable channels, many in English - a nice find after a period of travel in small villages with no news!). They provide bottled water every day (very nice!), but there were not basic items like tissues or a shower cap in the room.
The staff at the hotel were very friendly, although they weren't as strong English-speakers as what we had experienced elsewhere at hotels in Guatemala. Whilst we were staying there they couldn't accept credit cards (I think the machine was broken?), so ensure you have access to cash as a back up. The internet also wasn't up and running during our stay (I don't think they had their computers yet).More