We had never seen the PBS series and based on a friend's glowing recommendation we purchased the boxed set from Amazon. What an outstanding production! But be forewarned, it's addictive. We often find ourselves saying "just one more episode" way past midnight...highly recommended.
Just finished season 3...I see what you mean. I love this series but to say that they jerk the viewer around would be an understatement. It reminds me of the old spinning plates routine but you gotta love those Brits!
For those who enjoy Downton Abby another excellent Brit series carried by PBS is "Call The Midwife". The first two seasons were very enjoyable and Season Three is in the works.