Phonics Approach sets the foundation both for Reading and Language
I experienced teaching PreK children how to read using the phonics approach. I must say, it is a good start for them because it gives them the concept that reading is done from left to right and blending letter sounds. MOST teachers underestimate children's ability to comprehend such ideas but let us not forget that they are sponges. They absorb everything you say, and by teaching explicitly the rules of the English language (or any language's phonics rule), you will be making their reading journey a lot easier. They spell and read with high automaticity. Not only that, their comprehension is very good. They even know how to write their own phrases and sentences using phonics.
I also experienced teaching children who are trained to read using the whole language approach. First thing I have noticed is that they have a difficult time spelling, even simple CVC words. Compared to phonics trained kids, their phonemic awareness is a little poor. And their comprehension needs a lot of tweaking. Their reading accuracy is okay, but everything falls apart when it's time to spell and answer comprehension questions. Their writing skills are also poor.