I felt the same with my gen 2 Qashqai, 1.5 manual diesel, lousy fuel economy, terrible sound system, start/stop would cut in pulling out of junctions etc. and the seats were very uncomfortable (Acenta Premium) completely different to the ones in the Qashqai I took a test drive in.
I was glad to see the back of it after 6 months of terrible driving. I swapped to a 2L diesel manual Ford Kuga, much more comfortable and about 10mpg improvement.
The Seat drives OK (apart from the ACC) it’s just not in the same class as the R-Line diesel Tiguan I originally had on order.
Please excuse spelling/typos. Apart from being a clot it turns out I had one on my cerebellum that's now causing various problems!