Definitely too short... (spoilers)
I just finished watching this. I 'banked' them on DVR so I could watch them in a row, which I prefer.
The first two episodes seemed reasonably well-paced, even accounting for a lot of stuff left out (thanks for the great posts Silverwhistle). I'll definitely read the book now. I can live with some abridgement for dramatic purposes and even economics. But the last episode was almost ridiculous. Half of it was a cheapish montage to let people know how it 'ended.' As I started the last installment, about 10-15 minutes in, I'm thinking to myself that there's no way they can finish this in time. I even thought I might have missed a whole episode. Is the BBC in that dire financial straits?
Since I haven't read the book, I can't say for sure, but I don't think it needed 13 episodes (1974 version) or even 6 or 7 as some suggested. 3 or 4 90 minute episodes would probably have done it, which is about what most similar works receive. A prologue might have briefed the early events in the book I've gathered, like the council elections, etc.
One other thing. I don't know how it was handled in the book; but the treatment of Robert's death was ridiculous. How could people think that Robert committed suicide, when the fact that half the cliff fell off would be readily apparent to anyone who went to the estate. The newness of the calving off would be obvious. The dialogue makes clear that they knew he went off at that particular point, since they were calculating when and where his body would wash ashore. If that was the story they chose to tell, they simply should have had the horse spooked and Robert thrown (good rider or not) off the side of the cliff. Then it would be believable at least.
Loved the performances though Maxwell and Morrisey were particularly good (not surprisingly) and deserved a longer running time.