This national park is very impressive, because of its size first of all, then because its wild and well-preserved feel, then because of the vastness of its mountains. There are three peaks which are more than 3,500 m high, and many different hiking trails. On the South Africa side, the hotels are well organised and, based at the foot of the mountains, they organise ascents which last several days. The mountains certainly do lend a sense of charm. But actually, I preferred the Lesotho side.
I travelled to Lesotho via the Sani Pass, the only access point on the South side, where the mountain is at its highest. The passage is breathtaking, and I'd recommend you spend a night in a lodge right at the top. You can see the Sotho shepherds going about their daily lives on their horses, with their robes and their sheep. It's an incredible place for hiking. It's easier to access the park via the North of Lesotho: there, ecological tourism is well developed, and the villages open to tourists are already situated at a height.
I loved this national park because of the incredible scenery it offers, its intact San cave paintings, which I discovered with the help of a guide, and the traditional life of the Sothos in this region, which can be quite a struggle in winter. There are also great musicians who love to play somewhere where they'll get an echo from the mountains; don't be surprised if, in the middle of your hike, you hear some traditional chanting!