Currently running it on a shadow-specialized Ghoul (http://te4.org/characters/4384/tome/b30ebc65-c195-4fbb-9178-f77da9b16540
). At the moment (level 33) I've put in 1/1/3/1, and I'm liking it quite a lot.
Shadow Senses is very nice with one point - you can even target stuff your shadows see with Dark Whispers and Agony, although I've made a bug report on that, so it'll probably change. Still a useful talent. More points for higher sight range wouldn't hurt per se, but other things are more important.
The second talent looks decent, but is probably best for somebody with lower health than a Ghoul. The problem is that when you're low on health you're probably low on shadows too. Haven't used it much.
Shadow Transposition is awesome, especially for an undead. I've used it a lot to clear diseases or stuns (between ghoul barf and this talent, I haven't bothered to keep stun res at 100%). 3 points because two clears are safer in case there's a junk debuff together with the nasty one, and range 11 makes it very likely that there's a handy shadow in range. 2 points would be shaving it a bit close, but should be enough to be useful if you're feeling strapped for points. The teleport is nice, but I'd keep it for emergencies - you don't want it on cooldown when you need to clear something nasty.
Haven't used the fourth talent either, although I think it's worth putting a point into. The sustain cost doesn't matter much when you're low on hate anyway, so I think it's now a bad thing to put up before using stairs or traveling the wilderness and turn off if the fight is shaping up well. Maybe the design could be changed to have the cost decrease with talent points, to make it less of a one-point wonder.