I used my Zoom R24 on a recent project.... worked great except for a few things:

first, I'm not a pro with the R24, never cracked the manual, just kind of use it as is without a lot of detailed technical depth - meaning I may not be using it completely right in my situation..... but my history is recording engineer so I was comfortable with all that.

1. I didn't work up a good work flow (it was a 48hour film and I didn't have time to develop a good flow) and doing that before hand is a must since this is not a device dedicated to matching to video.
Think: how will I name these projects and maybe files for easy drop in later? Maybe record AUDIO SLATE so the tagging is IN the file?
Do I need to gate, compress, limit, eq at all going in? can save scrubbing and fixing later if you know what you are doing. If you don't, you'll make irrepariable damaged audio.

2. I created a new "project" every time they called "Action" but I didn't have time to NAME each project. All the sub files were named identical waves under folders like PROJ001 002 003 etc. So, I have to go through and rename every file to something that tagged it to the video clip.

3. Some have claimed these ZOOM things sync timing is not great for extended tracks. I didn't do anything extended to find out, but, sure that could happen. If you are any good with audio, you will know how to stretch to fit or adjust stuff so this is really no big deal.

4. I recorded two boom mics and then thought it would be fun to use the two live stereo mics built in to record room ambiance and maybe background environment for POTENTIAL use.
In retrospect this was a bad idea for THIS project because now I had FOUR tracks to sort out and label. After a few reviews I discovered which file was named what for what track and simply discarded those environment tracks since I didn't have time to sort though and they seemed mostly useless. Interestingly, there were pretty good quality and almost could have been used as primary dialog tracks with some tweaking. Sounded as good or better than consumer camera audio.

All in all, I still think it is a viable recorder for video stuff and could be quite handy with 8 inputs and full mixing availabe - as well as effects such as limiting that could help live tracking.
I also have an H2 that I think will be simpler and just as good depending on the shoot.

Good luck!