I have a HW friend who grooves to the NiosI dev environment, but the Nios2 IDE might as well be straight from the Alien Spacecraft. Personally, I'm a software guy and prefer the new IDE, but until Altera gets real about code size and fixes a truckload of teething bugs, I'm sticking with NiosI as well.
A halfway approach would be to use NiosII but with Legacy SDK support.
But IMO there are plenty of LE's on the chips that make sense to us financially, but very little RAM and flash. Right now NiosI makes more sense for us.
Ken