the main improvements over the note come from the one x's quad core CPU. if you compare them both in GPU benchmarks at the same ressy, they both perform quite similarly. when nvidia announced that the tegra3 would be 3x faster... they were comparing it to the tegra2.
so the main improvement will be in web browsing (android browser supports quads), smoother interface, and improvements in apps that support multicores (very few do aside from benches).
the only thing that peeves me about the one x is that it doesnt have a microsd slot, but im sure i can work around that with a usb on the go adapter since the htc one x supposedly has an mhl port.
at the moment, im just waiting for the other quad core phones to launch to see if there are any gems. the LG 4X interests me with its expandable storage (support for 64gb microSD), but it doesnt support the 850mhz band on 3G which would be bad for me since vodafone AU has a better 850mhz network than it does with its 900mhz network. theres also the galaxy s3 (same mali gpu but with quad core, so should perform on par with tegra3) and theres a fujitsu tegra 3 phone that has a 13.1mp camera and expandable storage coming soon as well, which should be quiet interesting.
i generally buy my phones outright... so when theres competition, theres a price drop, and thats a win for everyone!