It felt very much like the citadel in ME3. There are a bunch of faction vendors. I didn't spend too much time focusing on them but they sold gear and shading for coloring armor. There was a postmaster that you get your mail from, what's awesome is she actually would have any loot you missed during your last session, lost and found. There was a weapon vendor, also armor vendors for each class, you also turn in your mission items there for rewards. I forget the name but anyway there is a vendor there that decrypts blueprints basically. Ship vendors and even vendors for crucible marks and you can turn in stuff you find out in the wild or materials you get from breaking down weapons. Oh and then there was your vault. The views from the tower were amazing. Nice view of the last city on earth and the traveler.