I've got one of the Lansky 5 piece sets, and a Ken Onion Worksharp, plus some waterstones for the chisels.
Each has its place, the waterstones really are just for the chisels, so we'll ignore those.
The Lansky is nice because it puts a flat bevel on the blade, however the angle guide (and the Worksharp Precision will suffer from this as well) is problematic because while it may be a 15 degree angle at the closest point to the clamp holding the blade, as you move further away down the blade the angle will get shallower. I've not taken the time to measure/calculate the difference, but on a large butcher's knife, for example, the difference in angle could be quite significant.
The Ken Onion worksharp is great in that it is fast, accurate, and really does get blades scary sharp. However, it can be tricky to keep a consistent angle throughout the length of the blade especially on longer blades, and most importantly, it can only produce a convex grind. That's good for utilitarian knives, but sometimes you want a different edge geometry. And you really can't get that with the Worksharp.
