I went there yesterday (Sunday) and I thought it was fantastic. A really nice reception and a really low landing fee! Well worth a visit.
As previously stated, the cafe was closed (although apparently it will be opening soon), but drinks and sandwiches were available due to the enterprising ground-staff.
The PPR doesn't have to be faxed in 24 hours in advance - it can be done on the day of the flight, and if you haven't got a fax machine, then I think they will fill the form in over the phone (that was certainly the impression I got).
I have to say, I don't understand why people have a problem with hi-vis vests. They cost under £10 and you only need them for the crew not supervised passengers (i.e. you only need one). £10 isn't much of an overhead when you consider how much flying costs! We've got one in the back of the aeroplane, bought several years ago on a trip to Humberside, and it's worn whenever required. Also, I think that it is a health and safety requirement - not one imposed by Sheffield Airport. Most big airports do the same.