It’s excellent. Starting in Winchester the hills are more undulating, views OK and most of it is on wide farm tracks or well used bridleways. The further East you go, the hills get flatter on top but the valleys get deeper so the climbs are long and flinty and probably pretty slippery in the wet. Along the tops of the downs, you’re riding through sheep fields, so it’s very broad, grassy and covered in sheep poo, which is very sticky! There’s a gate to go through every few hundred yards, which can get a bit wearing, but the views are worth it.
Although the sign posting is excellent, there are a few places to get a bit lost so it’s worth having OS maps or a good guide book with you. And check for route changes (there is a big re-route around Exton) here and here.