In this rambling David Hare adaptation of Katherine Boo's brilliant book of reportage, we learn a lot about the underclass of India's slum communities – perhaps most valuably that they are very much like us. Actually that feels like a trite observation on my part. Probably more useful is that the show left me with a sense of shame that I ever needed to be reminded of the fact. The poor - not the Benefit Street poor of this country, but the eat-rats-to-stay-alive poor - are often assumed to suffer less than we would because they are used to it. Well, no one gets used to it.

However, the best that can be said of Hare's version is that it efficiently transposes the real lives that populate Boo's book to the stage. But only belatedly do we feel as if we know them intimately.

Director Rufus Norris evokes the sprawl of improvised shacks with a bravura you might expect of the man who next year takes over from Nicholas Hytner at the NT. A giant gantry revolves centre stage. Posters promising bright futures - or beautiful forevers - adorn the crumbling walls of Katrina Lindsay's set.

Monsoon comes and goes, locations between the rambling shacks of the slum and the shabby police station and hospital to which its inhabitants must go to be mistreated are seamlessly changed.

But for all the invention, the denizens of Mumbai's Annawadi slum are only vividly evoked when the production pauses long enough to give them the stage-time they each deserve.

The focus is on the families run by two matriarchs. The Husseins are one of the few Muslim families who live in the slum.

For income, they rely on Abdul (a watchful Shane Zaza) who sorts rubbish for recycling. His mother Zehrunisa, pitched perfectly by Meera Syal, is a foul-mouthed, fiercely protective matriarch.

Then there is Asha (Stephanie Street) a fixer with connections to a local party who solve anyone's problem for a price, whose daughter has become a conscientious objector to the corruption that has clothed and fed her.

With a cast of over 30, the show's intent is clearly epic: to evoke the scale of the sprawling slum, the depth of despair with which its inhabitants live and die, and the resilience of the human spirit.

Yet only occasionally and fleetingly does it feel as if these objectives are achieved.