I've had a Throttlemeister on my Triumph Tiger for five years and I like it. Yes, it's very awkward when you first try to use it, but it quickly becomes second nature and I never had much frustration learning.
It looks OEM (or better!), and is a snap to install and adjust. Like ANY friction-based cruise control, you will constantly have to adjust it on hills. Well, duh! On the other hand, I didn't spend a thousand dollars on it! They're usually available for $130 or so, and are often sold used for half that. I like its stealthiness in that it doesn't rob the grip of any real estate.
Now, my new ST has a very well-engineered and pricey lock, a BrakeAway. I like the feature of instant disengagement with front brake application. However, there are several things that I do NOT like about it at all. First, it robs 3/4" of my right grip, so my man-sized paw is hanging off the grip. Hate that. Second, it puts a huge amount of friction into the throttle so that its action is stiff and tiring. That's a real pain in the pie. Third, it can't be used with heated grips (per the manufacturer) and I rely upon same in my year-round commuting, and fourth, it can't be used with larger-diameter grips.
Since I plan on fitting both larger-diameter as well as heated grips, I'm going to ditch the fancy BrakeAway and will, almost certainly, be shopping for a Throttlemeister.