Darussalam publishes a copy of Riyad-us-Saliheen which, in addition to the actual ahadith compiled by Al-Nawawi, includes commentary by one Hafiz Salahuddin Yusuf.
The introduction to the collection provides no information on the commentator except that he had originally provided commentary on the Urdu collection. It doesn't go into any details as to his credentials or education.
In other words, it doesn't give any indication that this commentary is any more or less useful than the commentary of any random user on the street.
Google searching provides next to nothing except that he's from Pakistan (no surprise, given that he's contributed to the Urdu collection), that he's involved with the Darussalam Research Division (no surprise, given that this is a Darussalam-published collection), and that he was also involved with Tafsir Ahsanul Bayan (also published by Darussalam). Which really doesn't help except to suggest that the commentary was an in-house job (which doesn't necessarily impugn credibility, but in no way bolsters it either).
Who exactly is Hafiz Salahuddin Yusuf? What experience/education/expertise does he have that equips him to provide a commentary on such a classic collection? What, if anything, makes his commentary in any way valuable and/or useful?