The most important feature to me on a treadmill is footplant comfort. This nails it. If I run enough miles on a cheap treadmill, my Achilles and knees ache. However, there is more to a solid machine.
The Life Fitness Club Series Treadmill speed eases up smoothly and sensibly. It never jerks. Similarly, the incline is never abrupt. Very nice feature.
The buttons are an issue, reacting in a finicky, frustrating way. My make-do solution is, instead of fumbling with typing in numbers while running, I punch one of the walk-jog-run buttons, which takes me to a given speed. From there, I use the faster-slower button.
Entering my weight and speed and incline and it shows my calories burned. For me, this is just a curiosity, but it shows consistent data.
99% of the time, all I use it for is long long distance, up to 10 miles or so. For this, I am completely happy. There are plenty of other features I never use (the HeartSync workouts, for example). The buttons are a hassle, but once set, I'm good to run.
Life Fitness Club Series Treadmill