For a couple of years from 2018 to 2020 I was making quite regular trips to the Isle of Wight and discovered that by far the cheapest way to get there from my home was on a Network card discounted ticket from either Ockley or Horsham (Horsham, which is 7 miles nearer to Portsmouth Harbour is for some odd reason more expensive to buy a rail ticket from than Ockley, but the rail connections back in the evening to Ockley are much worse) to Ryde and then preload a 30 day multi single day pack of journeys on to a Southern Vectis key card for the bus as that worked out much cheaper than a day return bus fare as I had to get 2 buses each way to reach my destination and change at Newport bus station. Currently it is just over £4 a day on a 30 Separate Days key Southern Vectis pack but £10 a day for Southern Vectis's one day Rover single day bus pass ticket.
As I didn't then otherwise travel much by rail I wasn't really even aware of Plusbus back then but now I am I have consulted the Plusbus website at
www.plusbus.info and I can see that there are no Plusbus schemes in operation at all anywhere on the Isle of Wight despite the fact that you can buy a through rail ticket to Ryde Hoverport on the Hoverspeed hovercraft or to Ryde Pierhead on the Wightlink Fastcat and the Ryde Hoverport ticket also includes travel on the Hoverbus from Portsmouth & Southsea station (something loads of infrequent travellers who I saw get off the train at Portsmouth and Southsea and then pay cash fares to the Hoverbus driver were quite clearly unaware of as they presumably just bought their rail ticket to Portsmouth & Southsea and paid separately for the Hoverbus and also the hovercraft). You can also buy through rail ticketed journeys to West Cowes via the Redjet fastcat ferry from Southampton and to East Cowes on the slow Southampton car ferry. You can also buy through rail ticketed journeys to Yarmouth via Lymington Pier rail station on that slow car ferry.
So in view of the fact that the Isle of Wight has a large number of through ticketed rail station destinations (in Ryde, Cowes, Yarmouth and all the stations on the Island line down to Shanklin) can anyone explain to me why there are no Plusbus schemes at all covering these through rail ticketing destinations on the Isle of Wight, albeit that some of the rail ticketing arrangements are somewhat historic from British Rail days given that there are no longer any rail services from Yarmouth or East Cowes or West Cowes to Newport and that you can only travel from Cowes to Shanklin on the Island Line by rail.
Re Portsmouth Plusbus it only costs £2 a day with a Network card so I would say it is quite cheap (in relation to the £3 single journey bus cash fares) but the problem is that bus frequencies drop to as low as only every 20 minutes in the evening or on Sunday on the main No.1 bus route and so it is often as quick or quicker and more consistently reliable to walk to many destinations as to pay the £2 for Plusbus, especially if you are doing a journey that involves 2 buses, one of which (the No.25) is very infrequent indeed (less than hourly in the late afternoon and early evening).