I'd make a few changes
This remote does what it does reasonably well; however, a few enhancements would make this a blockbuster. What would I change?
First, I'd make it backlit. I shoot A/V in very poorly lit clubs, and it would be nice not to have to memorize the control layout of this unit in order to use it. This is especially true since the record button only puts the Zoom into record mode and cannot be used to pause/stop recording.
Second, I'd put level meters on it. This unit only shows you green (for unclipped), orange (for warning) and red(clipping). You have no idea how quickly the sound source is approaching clipping. Oh, and red and orange may as well be the same thing for HD sound file recording - "approaching" clipping really IS clipping.
Third, it's a PITA to adjust input levels if you are recording four channels (though in fairness to the RC-4, this is true of the Zoom H4N as well). And if you aren't right at the Zoom device itself, there's no way of telling if you've adjusted your level(s) all the way down to zero. This is a HUGE problem if you are recording a line-level signal which is already recorded at very low gain levels.
Last, there is a significant lag between when you hit the Stop button and when the Zoom actually stops recording. This is exacerbated when you record with high capacity (16 GB & higher) SD cards. This is only an issue because the Zoom itself is limited to file sizes of 4 GB or less because it is constrained by the FAT32 file system.
All in all, if your needs are limited, the RC-4 will accommodate you. If you have slightly more complex needs, you'll likely find yourself ignoring the remote and spending more time on the Zoom itself, which rather obviates the need for the remote in the first place.