Well, here's a map which turned out to be something else. It's got the wide landscapes, the terrain which affects gameplay, plenty of open sky... all the classic features.
It also has an unorthodox approach to game balance - if you want to cross the map, you're either going to have to fly and be a sitting duck, or battle your way across land bridges which serve as chokepoints. This really tests your team's ability to coordinate and over each other, which is unfortunate for me because my teams usually end up being filled with clowns. Heh.
Although the style isn't to my personal taste, it certainly looks good. The terrain work represents marshland pretty well, and the lakes just add to that effect, also adding a nice hazard for Scorpion and Manta drivers. The bases and small outposts covering the powernodes all have that rustic and abandoned feel to them, which is what the map aims for and succeeds at achieving.
The bases themselves have a great layout, they've got an open but well-defended entrance, and the frontal walls make good defense points. Base assaults can quickly turn into siege if the defenders are cunning. The generators are anything but easy targets, which can make all the difference in the end game.
What would I have done differently if I had made this map? Well, to be honest, it's a bit too open. There are plenty of long-range weapons available (sniper rifle, for one), but there aren't any good positions to use them. Sniping just leaves the players vulnerable. Also, the lack of ground cover makes Raptors a dominating force against infantry. Visually, I wouldn't change how the map looks. It looks different to other ONS maps, and that's a good thing.
This map looks great and plays great as it is, though, so I see no real reason to nitpick.
Give it a go. If you like Onslaught, there's no reason why you won't like this.