I took one for a test ride a few years back, one of the Harley dealers down here had a come & test day so I was keen to give it a go.
As mentioned above, it does pulse a fair bit at idle, causing the indicators & mirrors to shake like mad

also the cylinder head is right between your legs, so it does get rather hot. Red line is only about 6.5rpm, however as mentioned it has plenty of torque & pulls pretty hard. Handles great though. I was keen on one until I went & tested an 2003 R6 straight after testing the XB12R. The R6 for me was definitely more enjoyable, but I do like my bikes to scream all the way to red line

Still I would rather my 636
You should go to your local Harley dealer & see if they have one that you can test ride & see what you think of it. I love the design of the things, the look, the efforts made to centralise & lower the weight of the bike, great concepts & great designs.