We stayed at Valletta Nobile for four nights in July 2018 and found it to be a super stylish and well-located apartment. It wasn't totally clear to me that this suite is effectively in its own building - it has a private front door onto the street and the suite is at the top of two flights of stairs so, while it might not be the best for people with access requirements or mobility issues, it was fine for us and great in terms of privacy.
The location is excellent - it's a short walk to the sea which is great if you need to cool off in the summer months. As some people have said, the bar downstairs is noisy at the weekends and the church bells are right next door so can be quite loud, but we slept really well regardless on the really comfy bed. Valletta is packed full of vibrant bars and restaurants, so I think you'd struggle to find somewhere as central as Valletta Nobile that *didn't* come with a bit of "ambient noise". For us, it was all just part of the authentic Valletta experience.
The real stars here are Stephen and Brian. You can tell that they've put a lot of love into these suites and they really care about their guests. They booked taxis for us to and from the apartment; they were incredibly attentive on email before and during our stay and they gave us some brilliant and personalised advice about where to go and what to see while we were in town. Thanks both!