I'm gonna go against the current and actually discourage inscription. I know this IS a very popular tentative site and it's indeed a really nice fortified city. My issue is its OUV.
Mdina IS the old capital of malta, and It has been inhabited since the bronze age. Despite this It has little more than its layout to show for Its old age. There's nothing phoenician, or Roman, or islamic and there's only a couple of medieval components in the city (which are not really that remarkable). As such its strong suit IS actually its well preserved fortified baroque ensemble. And that I see as a problem
You don't need much time in malta to realise which architectural style defines the country. It's baroque. there's baroque In every corner, but that's especially true in la Valeta. Which does have some truly remarkable examples like the cocathedral and IS already (and rightfully) a WHS.
Imo Mdina IS left in a vacuum where Its inscription wouldn't really add anything new to the list. La Valeta already shows local baroque architecture, the history of the knights and has older and more impressive visible fortifications. At the same time the medieval heritage of mdinna, which should differentiate It from la Valeta, IS pretty much nonexistant. As such I don't think the city would adequately represent the fascinating pre-knights history of the island. So it's left without any clear OUV. Perhaps its best chance IS as yet another baroque city in the mediterranean. And there's fierce competition in that slot (Dubrovnik, val di noto, la Valeta)
So even though it's a really nice city and I would in no way lament its inscription...its a no from me. At least, until I get a good look at their criteria and comparative analysis.