We enjoyed our stay at La Abadia. The hotel is not luxurious but it's clean and quite charming. The rooms are small, but comfortable (except for the pillows). No A/C but the fan kept the room cool. The buffet breakfast is good... we particularly enjoyed the view from the dining room/balcony. Note: hotel has lots of steps.
It's a $3 cab ride downtown or a 20-25 min walk up/down hill. The hotel was quiet except for Sunday morning when the church bells ring.
Our only serious complaint is that the hotel did not have our reservation on file despite the fact that it had already charged our VISA card!! We had to go back and forth with them several times before this was resolved. If we hadn't checked our credit card expenses online before traveling, we may have let them charge us twice for the first night. If it hadn't been for this mix up, I would have given the hotel 4 stars.
Note: La Abadia actually has 3 hotels in Guanajuato, all of which are relatively close together. We found this out b/c we had to go to the other 2 hotels to find a place to park.