I stayed at Leslie's place for 3 nights and it was a really good stay.
Leslie is a great host. Very friendly and helpful. He provided me with everything I needed that I didn't have with me - iron, wall plug adapter, etc.
He was also very helpful with planing my stay - providing info on the places to visit in Malta and getting around.
One of the most important things - the place is kept sparkling clean. He has rules about hygiene that are clearly laid out around the apartment so there is no confusion.
The WiFi speed is acceptable and it covered most of the apartment (worked well in the room luckily, not so much in the kitchen).
As for drawbacks, I would have to really nitpick to find any... The people from neighboring apartments can be loud sometimes, if that's something that bothers you. And the bathroom sink had a bit of a low water pressure, which I'm sure was temporary (shower worked well most importantly).
All in all, I would definitely recommend this place - sparkling clean, great location, very close to the beach, with a great host.
P.S. One thing that should be mentioned that's often easily missed on AirBnB - this is not the only room in the apartment that's being rented, there is another one like it - meaning you might not be the only guest there. Just a heads-up in case you missed that info.