Disclaimer, I am not an expert in Arabic literature, but being from Lebanon, Arabic is my mother tongue. So this is only from experience.
Yes, knowing how to read the Arabic alphabet can help you more in pronunciation. Using Arabish is still possible but you won't be able to get the pronunciation 100% correctly all the time.
There are 2 main problems with using Latin characters.
- You lose the Arabic diacritics. They help a lot in pronouncing and accentuating every letter of a word correctly. However, even on Arabic text, you don't see these often. As editors usually don't bother with adding them. But you most definitely will see them in educational books, especially ones that are teaching you the Arabic language. And that will help you plenty when learning the Arabic language (After some practice, you won't need them as you get used to the pronunciation).
- There are several letters that are pronounced similarly, and when writing them with latin characters, you would use the same latin character. For example, the following 2 Arabic letters
ض are slightly similar but when saying the second letter, you basically add more bass to the sound of the letter. However, both are represented with a
d in Latin. So when reading them in Latin, you won't be able to distinguish which pronunciation to use. The same goes for
ط which use
ص which use an
If you check the comparison table in this Wikipedia article, you can see how many times the same Latin characters (I consider them characters and not letters because in some cases we use numbers) exists for multiple different Arabic letters.
So as a recommendation, if you have the option, use the Arabic script for learning Arabic. But using Arabic chat language isn't completely bad, but it definitely isn't as good.