Admittedly we haven't driven the entirety of 140, but that which we have was better than a freeway. Areas of it to the east were relatively free of traffic, and the landscapes variable and interesting - mild mountainous forest to high juniper desert to barren sageland. Some might find certain areas boring, but the freedom from other vehicles and the wide countryside is right up our farm-raised alleys.
Not far northeast of Lakeview is the hamlet of Plush where we've parked the coach in the "city" park and toaded 25 miles of gravel to gather Sunstones, or zigzag (toad only!) up the steep plateau to Hart Mtn. visitor center and antelope refuge. West out of Lakeview is Junipers RV Resort, a favorite park on a working cattle ranch.
It's been some years, and Oregon's taxes have been slim for road maintenance of late, so I can't speak much to surface condition other than it was excellent back when. I'll leave it here to more recent travelers to attest to that. Years of snow and ice and studded tires on bare pavement are not kind to our roads.
The stretches between Klamath Falls and to the east of Lakeview were plenty roomy, and good services available in both venues. But Lakeview to Winnemucca is pretty barren country, so make sure your equipment is prepared - it's no place for a breakdown.
Joel