Top gear is the best show on TV. I actually quite agree with their reviews frequently. The reason the X3 got trashed is for one reason only - Because they loved the X5 and saw no need for an X3 in the lineup. At least it didn't get as trashed as the X6 which they deemed totally and utterly useless.
It's an entry level SUV, and got an entry level SUV rating. Doesn't change the fact that it's a luxury SUV.