Are Bromptons worth the extra money?

Bod wrote....

Having bought my wife a very cheap folding bicycle
(about £100 from Halfords), I'm wondering why
someone would shell out 6 times plus that amount
for a folding bike.

I've just bought a second hand folder that would have retailed at around
£200 in Halfords. It's very obviously a cheaply put together bike - the
frame is reasonable, but the seatpost is a bit short, and doesn't extend,
the wheels are naff and the brakes are very poor.

I'm happy with it, considering I spend about 20 minutes a day on it. Any
more, and I'd be looking to upgrade a few parts - particularly the seatpost
with an extending one, the brake levers with deores (already put deore V's
on it), almost certainly the rear mech too, and then at some point the
wheels and tyres. At which point, it becomes clear that you would be better
off with a Brompton...