I didn't find the Road King to be comfortable for distances over 50 miles. This surprised me, considering its touring reputation. There were three areas of discomfort - shoulders, lower back and legs. Despite trying various handlebar positions, I always found that wind pressure put strain on my shoulders. My lower back began to ache because I wasn't able to change positions much at all. The same issue of not being able to change positions much caused my legs to become tired. With other street or trail bikes I've owned (BMW K100, Suzuki GSXR, Kawasaki KLR, Triumph Speed Triple, BMW R1200GS etc) I could move my legs back to the passenger foot pegs or hang them close to the road to stretch.
The bike looks great, so I enjoyed owning it for this reason, but be prepared for some intricate cleaning. All that chrome will lose its shine if you don't look after it.
Handling wise I didn't expect too much. It is a heavy bike after all. But the biggest scare is cornering clearance. You don't have much to play with, and if you get into a corner too fast (that weight is hard to slow down) the clearance becomes a concern very quickly. The more I rode, the more I realized I didn't have much of a performance envelope to play with, and started to feel unsafe.
Performance/acceleration is poor compared to any other road bike I've ridden. But that is a good thing I guess since you wouldn't be able to take corners if it accelerated fast... :-)
Side bags were great. I could fit my gear and work bag in them and the bike retained it's good looks.
Loved the sound of the engine after I put the screaming eagle pipes on. Standard mufflers have it sounding like a sewing machine off the showroom floor...
Detachable windshield is good. I enjoyed riding at lower speeds without the screen.