There was a cheat to render at full resolution (even 250% is not full resolution on a 1440p display) but it looks like the latest patch now has the option to render at "max" resolution instead of it being a cheat.
I thought the game lost something when rendering at anything other than the default resolution though, and some of the effects may not render correctly. The filter over the screen when the game is paused changes for example.
Liking the look may depend on whether you have any nostalgia for the Nintendo DS though.