I've just been having a look at the proposals for Leeds, and I can see the logic they've used, but it bears no relationship to how this city works. The existing boundaries are based fairly well on the way people travel down major arterial routes, but the new boundaries seem to ignore this completely, and just group the areas in clusters of wards that have far less interaction with each other.
Or to put it another way, I can currently travel to any area of my current constituency on one single bus, but to get to half the areas of the new constituency I'd have to get a bus into town, then another bus back out of town. local schools have also traditionally drawn their kids from along these routes, so the existing constituency is far more of a genuine community with stuff in common than the new one.
load of bollocks IMO.