I spent the long week end in Ryde and on Monday lunchtime I went to the Orrery. The place is literally amazing, especially if you like Lewis Carrol's Alice in Wonderland, and/or you want to have a laugh with funny vintage postcards (there's a museum in the cafe).
You can have lunch in the Orrery (with panini, felafel...), and you can also have the standard cafe stuff. I also ended up buying a 70s postcard about rabbits, as I saw a lot of them walking around the island.
Cons: Small choice