Robbie Williams has often played the clown prince of pop but his second album is laced with appealing maturity. It’s there in the sophistication of Neil Tennant-assisted “No Regrets” and the ambition of “Millennium”’s sumptuous fusion of trip-hop and Bond-theme strings. It’s most pronounced in the reflection and self-examination of his lyrics though. An admission of vulnerability set to an airborne chorus, “Strong” is a model of Williams’ s increasing depth and soul.