We loved it. The place was dead when we arrived at 8:30 am but really livened up. There were 8 different mariachi groups in the main plaza, which made my Mexican GF happy which made me happy. Just a real good vibe. The street and Mercado food game was a little week compared to the other places we have stayed (Reforma, Coyoacán and Queretaro), but we did zero research beforehand so might have not stumbled into the right area.
The town will remind you of some places in Italy and Spain as far as the hills in town. I think the one thing I wouldn’t do would be to get a place above town where you had to walk everyday up that hill (not because of my legs, but my ears having to hear about it the whole way up).
If you are going to be there a month, I would go check Queretaro for a couple days. We are in the Centro Historico and love it. Just added 10 days to our stay here. There is a Mercado called La Cruz a few blocks away that is a treasure trove of cheap, great food. Best tacos I have had in our 3 weeks so far have been there. If there are any other gringos in there I have not seen them.