First the good: Casa Marta has an excellent location, right next to the Plaza de Trinidad, which is basically where all the night life is in Getsemani. Despite being so close, the room we were in was actually quite quiet. It was clean and had everything we needed, although I don't think its aesthetics are going to blow anyone away. It was fine.
The people at Casa Marta are generally friendly, which is good, as they don't give you a key to the front door, so you need to basically ring the bell every time you enter the property. But they always answered with a smile and everything was nice.
My main issue with the Casa is that it's not really a hotel, B&B, etc. It pretty much felt like staying in someone's extra room. Upon arrival we were asked to enter our information into a spreadsheet, handed our key, and that was it. No welcome, no map, no suggestions of where to have dinner, local attractions, etc, etc . . . basically nothing that you would expect to get as the basic level of welcome when you check in to a hotel (and which we received at all other hotels we stayed at in Colombia). Again, the people weren't mean about it, they just didn't seem to care at all to offer help (e.g., we didn't even realize the pool was for our use until later when we read about it on Trip Advisor). Similarly, whenever I left the room to go into the hallway, I felt like I was staying in somebody's house, as they tended to be hanging out a few steps away (with a small child). This didn't cause any problems, but it wasn't very much like a hotel.
Overall this place was fine, as we had a guidebook and there are plenty of places nearby to have breakfast (which was not included in our stay), and there are late-night convenience stores for anything else you need. If you don't care about those sorts of services, then this place is a pretty good value for the money. If you do want that sort of attention in your hotel, then you should probably look elsewhere.