We've only stayed at value once and only used the ME once. Here was our value experience: We had a very late arrival after switching flights to come in about 10 hours earlier than planned. We were staying at the Swan for the rest of our trip, but there was no availablity - we made those changes the day of our trip. We decided to give it a shot and try a value and stayed at All Star Music, I didn't realize it didn't have room service, etc. or king sized beds or anything like that even though I've been to WDW at least 30 times in the last 10 years. We've stayed almost all the deluxes (except BW and AKL) and wanted to branch out - and it was only going to be for a matter of hours. It was a disaster and my husband was NOT a happy. All he wanted was room service beer and wings. For the price difference I would highly encourage you to just stay at your resort of choice. Our opinion was that they were Disneyfied motels.
Of course, others love them, I think different people find different things magical and that's what's great about WDW.