I have been using the iRiver products for about a year now. I liked them so much I gave away my MD recorders….
I find the audio to be very good. More than adequate for vows, readings, recording vocalist and the like. I use a Azden EX-503 lav mic for actual pickup. These are like $20 at B & H and work very well. These two together produce audio that is difficult to distinguish between the iRiver and my MUCH more expensive wireless mic.