The Needles covers a large area that includes the Amusement Park, Alum Bay beach, the battery & rocket test site. The buses stop outside the amusement centre that also has chairlift access to Alum Bay beach & summer season boat trip around the Needles. If you don't mind he climb back up, you can walk down the many wooden steps.
How amusing you find the park probably depends if you have children in tow or not! There are a few small rides, iced cream booths, hot dog stands, places to buy sticks of rock & a shop where you can fill glass items with coloured sand or buy them already filled. I seem to remember a fairly large restaurant.
The Needles & the Old Battery (Victorian Fort built 1842) are a twenty walk that can be accessed on the Southern Vectis tour bus. The small road is closed to cars, if I recall correctly. The Needles Old Battery is National Trust & is entered through a gated & short tunnel that's part of chalky ramparts where you pay to enter & look around the various windowless rooms that have artefacts & cover the history of the site that was built to repulse invaders. This tunnel opens onto a very large courtyard with the cannon placements to the right & straight ahead that overlook the western approach to The Solent. There is a building that resembles an airfield control tower that's a museum with a cafe at the top with fine views of the Needles, lighthouse & sea. Back out in the courtyard are steps down to the tunnel that about 50m long leading to the large search light placement that overlooks the Needles & lighthouse.
Back towards the park on the right is the rocket testing site where the Black Arrow & Black Knight rocket engines were tested in the 1950s (Highdown Test ite). Most of the buildings were demolished but some of the bunkers survive & worth looking around read more