The screen is the immediately impressive quality about the One X. Photos are mediocre in good lighting/outdoors but excellent under very dim light. Speed is alright I guess, but runs out of ram more often than I'd like (thus clearing an app out of cache causing a reload when switching back to it).
To me, the most impressive is its battery life. I've gone through too many Android phones with poor battery life. The (snapdragon) One X is the only Android phone with acceptable battery life to me. So it's either iPhone or One X. Everything else dies on me at some point in the afternoon/evening.