When I first bought Knights Rush, I had an iPhone 3G, and I held off writing a review because it wasnt very playable. It would freeze often, the sound would cut out, and it just wasnt worth the effort. Now that Ive upgraded to an iPhone 4, the difference is night and day. Knights Rush is very playable, and Im enjoying it quite a bit. The music is very epic - reminds me a lot of Pirates of the Caribbean and other Hans Zimmer scores. You can see the graphics for yourself. I havent yet had any savegame issues. I think Knights Rush is certainly the best of its type on the iOS.
Some things I think might make it better: Make the three warriors feel more different when playing. Aside from two special attacks, they largely play identically. Considering the three warriors are guy with shield, heavy guy with hammer and twin dagger guy, I think a sharper focus on defense, strength and speed respectively would make things interesting.
Each character has two traits that can be leveled that give increased exp. This was a nice balancing act when your abilities reset after each campaign, but considering levels are permanent now, they dont seem right. Anyone who plays long enough will max out a character, and they become obligatory first things to level. Id replace them with more tangible benefits and adjust the exp accordingly.
Lastly, unless my experience was a fluke, Id adjust the play requirements to suggest a user have no less than a 3Gs, because my 3G simply couldnt keep up. Its a great game if youve got the specs for it. Early iPhone models dont.