Based off the screenshots your map looks rather flat. This doesn't mean your map is void of all height variation but the play spaces look flat and open. Try adding a bit more interesting geometry around the level. One of the main parts of tf2 is height variation. this allows one team to have a tactical advantage over the other player, simply by moving around. This is great because it stimulates active game play and increases the amount of ways to play any given part of a map.
If you want to make a fun enjoyable map, try standing in any part of any map, valve maps are good, and ask this question. If I was on Red/Blu how would I beat another player at any other point on the map. I'd recommend you ask these questions with specific classes as well. For example, how would I beat a scout there as soldier here.
Got that? okay, how many different options did you have? Was there a clear best option? An only option? Was there a hard choice between two positions, health and ammo or height? These are good questions, ones that, as mapper, help to find what makes interesting and fun level design. Try asking these sorts of questions around your map. Don't take, I can move around this field, for an answer either. Be honest with yourself. If you can't think of a good strategy to play your own Map no one else will. Remember this, if there's no way to gain an advantage, there's no Strategy. If there's no strategy, it's a battle of stats not skills. That's not fun.