Devanagari script has one serious problem as I see it. When used to write Sanskrit, it is actually too phonetically faithful, and represents the sounds so accurately that the morphemes can be obscured. The classic analogy is the /s/ which represents the plural, as in cats, but sometimes it is pronounced as a z, as in dogs. In either case, however, it is written as s, because this represents the phoneme, not the actual pronunciation.
In Sanskrit, however, these different sounds would be written out, as if in English we wrote cats and *dogz. Furthermore, it becomes more complicated than this, because of sandhi. Therefore if we apply devanagari principles to English, a sentence which we write as I have to go to the store might be written as *I hafta gotth' store, depending of course on accent and dialect.
All this makes Sanskrit easier to pronounce correctly, based on the written form, but it really obscures words and word relationships, at least in the written form.