It's enjoyable on an iPhone 5 since you can use variable zoom, so it should be even better on a 6/6+. I'd say go for it, and they definitely fixed the minimize glitch, first thing I tested.
Not only is it easy to un-minimize as it's got a lot more touch sensitive space, but it's actually harder to minimize it in the first place, as they shrank the minimize button to reduce accidental presses. Running flawlessly for me so far, even got all the extra character packs. They include new areas, though I hope you're not required to use the characters to access the areas, but it's possible you do.
If anyone knows if the new areas can be accessed without needing the characters from the same DLC packs, that would be great information