I've taught for over 30 years, many of those in Foundation and Year 1.
Synthetic phonics is by far the most effective method for teaching children to read. I was so glad when the Rose report came out and all schools started teaching phonics systematically.
By the end of Reception, most children can decode simple words that include the sound/letter correspondences that they have been taught.
Those people who say that English isn't a phonetic language are misled by the fact that we have a complex code.
Chinese, for example, is a character based language where you have to learn to recognise countless characters which represent different words.
English is phonetic because each letter shape represents a sound. Some languages, like Spanish, have a fairly simple phonetic code and consequently fairly low rates of dyslexia.
English has a more complex code where a sound can be represented by different combinations of letters (play, rain, they, cake, sleigh) and one group of letters can represent several sounds (tough, though, through, bough) so, not surprisingly, we have higher rates of dyslexia.
The complexity is because written English is essentially a mongrel language because of our history - Germanic from Anglo-Saxon invaders; French from the Normans; an extra h in words like ghost because of Dutch printers trying to make words look more like the spellings that they were used to; silent letters in words to reflect a medieval pronounciation - the sounds have been dropped in speech but are still there in the spelling etc etc
Some words do need to be taught as whole words to beginner readers. But that's not because they aren't phonetic, it's because they're useful, common words but are beyond a beginner reader's current phonic knowledge.