According to the prestigious Africa Freak website Niassa Special Reserve is one of the Mozambique's best conservation area, ranked 68 out of 105 conservation areas in Africa.
The recent publication characterises NSR in the following terms:
"The largest protected wildlife area in Mozambique, Niassa Game Reserve is 42 000 km² of a diverse and ever-changing landscape. With a massive population of wild dogs, it is one of Africa’s top nature reserves to witness these magical creatures. Isolated, remote, and visited by few, the park offers a rugged bush experience."
The same list also includes other mozambican conservation areas namely: Gorongosa National Park and the Limpopo Transfrontier Park.
Source: https://africafreak.com/national-parks-in-africa