Since the last paragraph of the question says, "For the purpose of this question, I'm looking for answers geared more towards English", I'll assume that the OP mainly wants to know if phonics is effective for English.
The challenge of using phonics in the teaching of English is that English has 26 letters but 44 sounds (or phonemes), and that certain letter combinations can be pronounced in various ways. For individual letters, take for example the 'o' in "hot", "note", "woman" and "women" (four different pronunciations). For letter combinations, take for example the 'ou' in "bough", "bought", "boulder", "boulevard" and "tough".
The USA have gone back and forth between phonics and the whole-word approach. The British Department of Education promotes phonics, but the article Five things about phonics (BBC News, June 2012) points out that:
The government's phonics-only approach is controversial, with many teachers and educationalists advocating a more balanced approach in which other reading strategies are also used. "Some children will need more phonics-teaching more than others," says Andrew Lambirth, professor of education at the University of Greenwich.
The English Teachers Association NSW in Australia published a position statement that points out, among other things, that phonics is just one part of a bigger set of reading strategies that learners are taught. The position statement contrasts the Australian approach with the strong emphasis on phonics in the USA:
The USA through its national program, Reading first ,can be said to have effectively advocated phonics as the main method of reading instruction in US schools - with legislation reflecting a long history of phonics-based instruction in the US. In the 2003 international PISA test despite the "overwhelming scientific evidence" in favour of phonics-based instruction, 15 year-olds in the US scored significantly worse than Australia with its more inclusive reading instruction. Australia, in fact, was beaten by only one country - Finland.
The Australian position statement also quotes a paper by Stephen Krashen, which says, among other things, that the general public and the media in the USA support phonics instruction without being aware that there are several different phonics methods (intensive, systematic phonics, basic phonics, zero phonics).
Based on this, a phonics-only approach to teaching English seems too limited.
It is not so easy to find information about phonics for languages that use a different writing system (i.e. not the Latin alphabet). There is some evidence that phonics can be used for teaching Arabic (see e.g. A First: Cartoon To Teach Arabic Reading Through Phonics, December 2015), but I have not found any evidence about its effectiveness compared to other methods.
People have also applied phonics to the teaching of Russian. According to the article Russia has phonics debate, too (Baltemore Sun, 4 March 1998), the teacher Olga Viktorovna Pronina argues that the whole-word approach required too much memorisation because word endings change, and children who learnt to read a word according to the whole-word approach can't apply that approach to other words. However, Russian has a much more straightforward relationship between spelling and pronunciation than English, so it does not serve as a good argument for using phonics in languages with a complicated relationship between spelling and pronunciation.
So, until someone can point to evidence about the use of phonics for other languages and other writing systems, the question cannot be answered definitively.