The speed feels bit annoying at times, but it's tolerable. I don't usually walk any longer distance if I can avoid it, and would still use teleports on higher speeds, as the same stuff would still happen while I'm walking. And while in action the speed feels right, I have bit time to think what I'm going to do and more room for mistakes, too (say, misclicks won't be that bad etc). The game's still strategy game somewhat, not a shooter or such.
In DotA the speed was nice, and at first DG did feel really slow paced. But they're different games. And I really hated deaths due to misclicks or lag in DotA, hasn't happened in DG.
As for maps, they felt disappointing for a while, too. I miss forests and hills, with lots of places to get out of los and run away, or hide and gank. They would still be great, but the current maps are pretty nice too. It's still possible to ambush people, and the flags add lots to the complexity.