The comments as the audience filed out at the end – “Better than Britney, much more fun”, “So likeable, just so nice” – were not as you might expect from a show featuring a heavily tattooed rapper with diamond teeth and a history  of gun and drug charges who proudly told CBS’s Katie Couric earlier this year, “I’m a gangsta”.

But Lil Wayne, it turns out, is no ordinary gangsta. The 27-year-old from New Orleans is not only one of the biggest-selling acts in rap, “The Best Rapper Alive” according to one of his songs, but he is also one of the least predictable.

His rhymes are surreal ghetto-rap reveries, delivered in a raspy voice like a hip-hop George Clinton. The usual rap machismo about weed, women and cash goes hand-in-hand with more adventurous career choices. In 2005, the year he released a platinum album, he enrolled at the University of Houston to study political science. Later this year he is to release a rock album, Rebirth.

There is something “you need to know about me”, he declared at the start of his set: “I believe in God.” The teenage boys surrounding me looked confused, but perked up as the dreadlocked rapper launched into a barnstorming version of “Got Money” from his last album Tha Carter III, all catchy hooks and grinding southern rap beats.

It introduced a disjointed but entertaining show. A backing band added heft to the music alongside a DJ. “A Milli”, yet another track hymning “the almighty dollar”, featured an awesome trouser-flapping bass-line that is missing from the weedier recorded version. But, less happily, the backing musicians also acted as enablers to Lil Wayne’s rock star fantasies, which chiefly consisted of egregious guitar solos and gruesome attempts to sing.

Perhaps the shifts in tone made sense to the youths covertly puffing marijuana in the audience. But even they must have been puzzled by sequencing that saw a maudlin track about “lost lives” being followed by the idiotic misogyny of “Every Girl”. Yet Lil Wayne, an energetic and oddly engaging performer, made light of the inconsistencies. Like his crossover predecessor Jay-Z, he wants to turn rap into a live spectacle, like a rock or pop concert. The results at the Apollo were erratic, but his efforts were wholehearted.