I saw him at those three Hammersmith shows too, second or third night I believe. His voice was fine, his stage raps cringeworthy and the band was in fine jammy mood. Turner was a bad choice as a DP vocalist, but for some reason the Slave and Masters album and some shows of the tour actually worked, DP was laid back with Turner, to me it sounded sometimes like a Dire Straits influence had crept in, but Blackmore seemed comfortable with it and hence inspired. But it was clear that it couldn't last and that the novelty effect would wear off. At the time, I thought the tour refreshing because it had them revamp their setlist which had become stale. And Turner showed guts by opening with Burn. More important, most of the SM tracks worked well on stage.
That said, Turner is absolutely charisma-less on stage. None of Gillan's witticism and hilarious puns ("There was a football team from down where I lived in Perfect Street. The Perfect St. Rangers. What a great team! This is a song about them ..." and then DP play Perfect Strangers!), none of Coverdale's mix of macho gaucheness and gentlemanlike behaviour, none of Bonnet's off-the-wall humor and sheer intrepid energy, none of Dio's gripping command. Just some dork from New Jersey who can have a pleasant voice but is kind of embarrassing to be seen with.
Uwe