I stopped by here on a Tuesday afternoon; they were open although it was a jour férié. The café is…read moresmall but cute with a nice atmosphere and is run by a kind, soft-spoken gentleman. There were 8 tables inside (each seating 2 people, but I'm sure they could be pushed together to form larger tables) and 3 plushy chairs; there were 2 or 3 small tables outside with a large umbrella.
There was a good list of teas on the menu, most for 3,50€ but a few premium ones were more expensive. There were also tea leaves and tea accessories for sale. You could smell-test the teas inside before ordering. There was also a small menu of lasagnes, quiches, etc "fait maison" and a small selection of sweet treats on display as well. I ordered a pot of lapacho tea for 3,50€, which yielded about 3 cups, and was steeped with care. I was given a little hourglass set to time the tea steeping, which was cute.
The atmosphere is very calm and tranquil; I think the books all around encouraged people to speak in hushed voices as if it were a library. There was 1 woman working on her laptop, and it seems like this would be a good place to get some work or reading done, or to have a calm conversation. The owner was happy to provide the wifi password when asked, and the connection was pretty reliable. One woman brought her 2 dogs and tied them up outside; the owner offered them a bowl of water, which was very sweet.
The bathroom was pretty pristine, although you must use a set of fairly narrow stairs to access it, so keep that in mind. I stayed for about 1.5 hours and was never bothered or rushed. I paid with cash but it appears credit cards are accepted. The café is very conveniently located in the centre-ville, not far from the cathedral. There was air conditioning; however, it is worth noting that this was not terribly strong so you might still be a bit warm if you're used to the AC in the US.
I really enjoyed my tea and the atmosphere here, and would highly recommend stopping by for a nice conversation or to get some work done. Although I did not try them, the pastries looked enticing and 1 of the other customers described the lemon meringue tart, a house specialty, as amazing.