This here is the 1995 edition of Colloquial Welsh. I bought this edition because it was all I could afford at the time. However, after getting I was pleasantly surprised that the current audio available online on the publisher’s website (for free, by the way) is nearly unchanged from this printed edition you see here.
I found the course itself very thorough and easy to follow. It does a decent job covering the various dialects in Welsh and how they resemble and differ from one another. This is also reflected in the audio. Even better, the audio is of very good quality. This makes it easier to absorb the unique sounds found in the Welsh language.
Polyglot in Progress 