If you're a European or North American traveler used to corporate hotels, the Bauen is neither comfortable nor hospitable. In addition to the badly worn and faded interiors that other Web reviews prepared me for, the air conditioning was also not operative (in late November with a west-facing room this was a real discomfort), the storied basement disco lounge was closed, and the staff were even surlier than I would have expected of survivalist porteno service employees.
That said, the hotel cooperative is giving it a good effort and the basic hotel services are fine (I used the hotel laundry service and delivery was prompt and tidy). The real reason to stay there is to give business to a group of people who took over an abandoned property and reopened it for business to demonstrate their right to work. Legally dicey, and hardly an example of a government looking out for its people, it remains an intriguing case of labor disputes-- in North America and Europe, these are usually executed by not working, where here we have a mostly functioning hotel run by people who needed work to maintain their livelihoods. If you don't see any merit or legitimacy in this position, there's no especially compelling reason to stay there. Don't go expecting the worker cooperative story to be immediately apparent, and if you like comfort and have a few extra pesos to spend, look for something plusher.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC