Debating about getting one. Always wanted one but was talked into a 954 instead. Got out of road bikes after I sold it.
In my earlier days of riding I was mentored by someone who was very pro Jap bike, anti-Harley, and indoctrinated me to the idea that inline 4-cyl bikes were always better, period. Looking solely at the engine there's an argument to be made for that since they're smoother, more powerful, can rev higher, etc.
As I rode more bikes and started to develop more of my own opinions on the matter, I more and more got to the point where I didn't like I4s for a few reasons. First, they're wide and thus require a wider motorcycle, specifically low around the frame meaning there are fewer options for where to put your legs. Second, they tend to be inherently revvier engines, which is fine on the track but on the street torque is king.
So, I got to the point where I really liked V-twins, and I tend to think that looking at the application as a whole, the V-twin is the best engine choice for a motorcycle, with the V4 being the second best. Narrow (unless you go the Moto Guzzi route), torquey, and also I prefer to have some vibration rather than the sewing machine smoothness that most I4s have.
I bought my RC51 because I wanted another liter class sport bike, and wanted the benefits of the V-twin. I'd previously had a Bandit 1200S, V-Max, and had most recently sold a VFR800i. Also throw in there a Suzuki TL1000S. The RC51 was my favorite out of the liter class sport bikes I owned. The engine was very torquey, great visceral characteristics. Just shifted and sounded great. When I bought mine it came with some aftermarket exhaust that was more or less straight pipe. We called it the "Mad Max" bike for several reasons, the pictures will explain it best. I ended up putting a stock exhaust back on it and was very happy with that. I also had put a cheap JC Whitney tour pack on the back, which made it quite practical. Had a lot of fun riding that thing around the back roads in PA.
Visceral qualities, it excelled. However the particular bike had more issues than I felt like fixing, and I eventually sold it. I've been getting the itch for another sport bike, though, which is ridiculous seeing as I don't even ride the two motorcycles we have at all.