He hasn't released a full studio album since November 2004, so Eminem's sixth album is one of the year's most eagerly-awaited releases.

The Detroit-born rapper has had a difficult few years, first cancelling his 2005 tour and checking into rehab for a dependence on sleeping tablets, then suffering depression after the death of his best friend, D12 rapper Proof, in a nightclub brawl in 2006. Earlier this year, Em admitted he'd considered suicide when he was at his most depressed.

Now the US's best-selling artist so far this decade (32 million since 2000, with The Beatles second at 27 million) is back — and using rap as his therapy of choice. As usual, 'Relapse' offers an intensely personal view into Eminem's brain — which is even more warped than on his previous efforts.

The man born Marshall Mathers doesn't pull any punches, and his new outing deals with subjects that'll make even his biggest devotees squirm: from his alter ego Slim Shady's lust for murder and domestic violence, to a song describing his mother's love of Valium, to the demented (and aptly named) 'Insane' which describes in painful detail a boy's abuse by his stepfather.

There's also yet another track devoted to Em's seeming obsession with pop star Mariah Carey. Their "feud" has now extended over seven years and four albums (his 'The Eminem Show', 'Encore' and 'Relapse'; her 'Charmbracelet'), since they dated briefly back in 2001.

Check out the eerily prescient lyrics to Mariah's 2002 track, 'Clown', which was a barely-disguised response to the rapper's first musical attacks on her, and accurately predicted what would indeed happen to him between 2005 and 2008.

Ultimately then many of the album's themes sound familiar (and even a bit boring — especially the Mariah obsession), but after a few listens, Eminem's lyrical genius shines through (even if your admiration matches that squirming).

If you're a fan, you'll be glad to have him back. He's promised another album, possibly before the end of the year. If 'Relapse' is anything to go by, that's another one to look forward to.