I don't like it much either. It's clunky to read, and also by portraying one accent phonetically, you implicitly suggest that the speech of other characters in the book is "unaccented", or "normal". It gets especially weird when the "phonetic accent" more closely resembles my pronunciation than the rest of the dialogue does, because suddenly you have to start wondering, "So how is everyone else in this book pronouncing that word, if the way I usually say it is spelt out phonetically?" and that just drags me out of the story...