One thing that I've noticed through the years, is that when a rider who is used to bikes with large, relatively slow-turning engines like most cruisers have, rides a sport bike for the first time, they tend to 'grab' way too much throttle, way too soon.
The large (relatively) sportbikes use an amazingly small throttle rotation to get things going, and in 'normal' riding situations, again...small throttle movements get things done.
With my Hayabusa for example, riding in the Black Hills, when climbing the sometimes substantial upgrades around here, I could feel my throttle-hand movements to go up the grade while maintaining highway speeds (more of a backward 'pressure' on the grip rather than a rotation), and If I would look at my throttle hand, any visual movement was almost imperceptable.
My VTX 1800 would require a lot more throttle rotation at the grip to move up the same grade, while I would suspect that a 1500 Vulcan would likely be almost wide open to accomplish the same thing.
On large sportbikes, the brakes are great, and the throttles can be relatively abrupt and linear, with little 'lag' in engine response.
They are easy to ride, and 'safer' in some ways than other types of machines, but their very 'sharpness' and competence also can mean that they can be very unforgiving of foolishness or mere unfamiliarity.
Be careful, and once you can relax a bit, have fun.