Its useful in a non-impale Shadow build, but mainly shines in a LoN build. Its a very "lazy" sort of playstyle - You use one bomb, and the entire group dies.
Note that Chanon Bolter will bring ALL mobs in a 30 yd radius to the original Sticky Bomb target before it begins its CD, so its useful for grouping.
Unfortunate that virtually all DH builds require Dawn, limiting the ability to make builds, because otherwise using Sticky Bomb as a spender, Chakram as a generator would be a pretty strong AoE build.
Some other things - The lesser bombs from the power do not have a limit (Although you can't actually get out 3 sticky bombs before they go off unless you have something like 90% ias). Each lesser bomb deals full 915% damage. Explosion radius is fairly small, which makes Chanon Bolter a good choice if you are going pure Spike Trap. Recasting the bomb on the same target does not overwrite it, allowing for ST damage utilizing this.
It would be nice if blizzard implemented more sets for skills that aren't being used (In the case of DHs, Spike Trap, grenades, and Chakram-esque build would be cool)
Imho a nice start would be Grenadier to affect also Traps, to have a definite passive skill that has a clear use like Ballistic has.
Then yes, we need definitely a set to workk with these skills - i'm sure that LoN can make the skill itself usable at a decent level, but still LoN "suffers" from the fact that there will always be a "best build" so running with a suboptimal setup will only hinder you on the long run.