I'd assume the IGH is both heavier and less efficient. So what? A pound of extra weight isn't what keeps riding from being fun, unless you like to race your friends and their bikes all weigh less---and then the weight is more fun, because it gives you an excuse for losing.
The trade-off are clear---the bike is Always ready to ride with nothing more than a squeeze of the tires to make sure they are aired up. After a ride the rider can park it and forget it and it will be just as ready whenever s/he picks it up again.
The lost half-watt isn't what's keeping the rider form climbing that next hill or whatever .... it is Not a high-performance bike.
But just as a modern household sedan can outlap a lot of performance cars from 30 years ago, if driven to its limits---most modern bikes have performance capacity Way beyond what most riders use. (If you aren't sliding and saving the back end at 65 mph on fast downhills or sprinting at two thousand watts .... ) This rider has sacrificed some of the extremes of performance s/he would never have used anyway to have a trouble-free, always-on bicycle.