I have this tank and I really like it. I do keep the water level up in mine and my betta is fine. He knows exactly where to go to get air. If you're not comfortable with doing that or your betta frequently tries to breath over the glass area then you can just lower the water level a little. It does take away from the 3D view but it's still a beautiful tank either way.
My edge only has my betta, one assassin snail and some hitchhiker pond snails in it. It's also planted so I don't vacuum the gravel. Water changes are a little annoying since you need to use a small cup to scoop the water out, it's not that hard though. I also have the mini fluval heater in mine, it has a thermostat that is automatically set up 78F, mine rarely turns on though since my house is usually at 78F already. I also replaced the stock halogen lights with MR11 LED's. The newer model of the Edge comes with an LED bar but most stores aren't carrying these ones yet.