Being chronologically sandwiched between Sad Wings and Stained Class has done Sin After Sin no favours at all. The problem being that this album has an entirely different feel about it, however, it should be enjoyed on it's own merits and not compared to those other two.
It's a cracking little album and quite a bold move from the band as well after the huge opus of Sad Wings. Three of the tracks on side one are absolute Priest classics - (Sinner, Diamonds and Rust, Starbreaker) - whilst the fourth track, The Last Rose Of Summer, is one of those beautiuful ballads that Priest used to do so well but have been sadly lacking in some of their later work. Side two is almost a concept and in my opinion they hardly put a foot wrong apart from the guitars sounding a bit Brian May-ish in places. But so what! The album finishes with Dissident Aggressor which has lyrics that may not sound so shocking these days but seemed incredibly violent at the time and the song has been cited by the likes of Lars Ulrich as a major influence.
Overall, it's not as hard or heavy as SWOD or Stained Class but it is fast, punchy, different, hugely enjoyable and I love it.