What is the author's style in Trainspotting by Irvine Welsh?

The most apparent aspect of the language in Trainspotting is its use of Scots dialect to establish character. As first glance, indeed, the dialect looks like a language other than English, with "ah" replacing "I" and "whae" replacing "who." Soon the use of dialect becomes more apparent as a way to distinguish one narrating character from another. Spud and Begbie, for example, are the most heavily accented; Davie and Sick Boy markedly less so.