Well, since Rishab gave the go-ahead to "let the rambling continue," and all...
I can see how it could be useful for some builds and/or in certain situations, but the amount of Skill Points needed turns me off to it, as I'd rather spend points elsewhere. Besides, there's Blade Barrier for keeping the hordes at bay when necessary, and it only needs 1 point to be effective. Void made a good point about old Premeditation skill being nothing but a point sink, but Psychic Scream is sorta the same in that it needs so many points to be useful. Of course, that will change when cross-skill timers are no longer a thing. *heavy breathing*
Yeah, it's a PITA to use, but I've seen it used successfully and to great effect. I don't think many people use it though b/c other sin builds are just easier to handle.
I agree with the people saying D2 Charm mechanic is stupid since Charmed monsters can't be attacked/killed. It makes Charm virtually useless and a PITA b/c of having to wait for the effect to wear off before killing the monster. I'm sure it can be used effectively, but for general play, as it is, it's more annoying than anything.
To be fair, I don't have tons of experience playing Assassins, so take my comments for what they're worth.