Depends
Nas drives use different protocols to share files, some will share .iso's, some won't. Which protocol you're using is dependant on (a number of things, including) what you're using to play the media, so it depends what your 'network devices' are.
Computers (windows, mac, linux) can use SMB, NFS or AFP. You see a folder structure like you would on any other hard drive, you can browse to the iso file and mount it, or play the iso directly in vlc.
Android, with a file manager which can see network as above (I like ES file explorer), then open the iso with VLC.
That's probably about it for the positive news
Everything else might struggle. Many other devices, such as blu ray players, WD Live will use DLNA. You'll struggle to find a nas with a dlna server which does ISO's. If you want to watch on any iOS devices, you'll struggle.
For best compatibility you could rip to a friendlier format like mp4, which DLNA would share to many more devices.