They are stylistic features and I can't say if it affects legibility or not. The features of Naslatliq that I see are:Nathan Zimet said:I am wondering are there any specific details in the letters that give it the hint of Nastaliq? And would you say the calligraphy is beautiful and/or legible?
This is also a personal choice. In Iran readers are more used to typefaces which are now called allegedly Eurabic or Neo-Naskh or Simplified Arabic which utilize the four paradigm shapes per letter. This is also without having the ligatures in text and is only a custom and what people are used to in daily life while reading text. In Arab world it seems that readers are more used to see ligatures in text. If you take a look at newspapers of Arab and Persian world, you will pick up these features in the texts. I would go for a typeface that is well designed regardless of how it utilizes the script in conventional type systems. The curves and how letters connect to neighbors is very important. I would also prefer not very high and low horizontal (asc/des) metrics only because it doesn't appeal visually to me.When you say you would go for a Naskh typeface for scientific/scholarly use, do you mean simplified arabic (like a lot of system fonts) or a naskh with traditional forms?