Maintaining the tank will be a bit more work. You have to test for salinity, and preparing the water for changes is an additional step. Cleaning is pretty similar to FW--though you have to deal with salt creep. FW topoffs for evaporation are critical in BW, since the evaporation increases salinity, and can cause problems.
Otherwise, it's not that different to maintain. You will be limited in what plants can go in, as well as fish. There are many, many fish sold as brackish that need full marine conditions as adults--and compared to either FW or SW, there are not that many BW fish in the trade.