This place isn't for everyone, but it offers good value. I'm currently staying in a large room with private bath, large desk, ceiling fan, and window to the outside for COP12.000 per night. Before that I had a smaller room with private bath for COP10.000 per night. These are the best prices I've found in Colombia. The wifi internet connection is reliable and fast (Skype works great; download speed is 4 Mbps according to speedtest.net), and I've gotten along great with the staff.
I'm in Santa Marta for research, not for partying, and I've found that Miramar suits my needs well enough (although there are moments when I wish I had AC and I also miss having access to a kitchen) . It's clean enough for my standards, but then I've done lots of travelling in the so-called "third world". If you're on the dainty end of the spectrum, this place may not be for you (see the other reviews), but if you're someone who doesn't mind "roughing it", Miramar offers excellent value. I recommend having a look.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.