Before my current Skeleton Brawler that is a disaster (you really need to find awesome random gloves to have the class shining, most early glove/gauntlets artifacts aren't great), i have been running a Doomed class as i wanted to experiment a bit more with it.
That Doomed was doing well at surviving, but roughly at level 15 i just gave up because i simply had no fun at all.
The shadows themselves are strong, i had 3 of them running around, but the problem with them is that unlike summons that are always usefull in attacking or helping you get some breathing distance between you and a strong enemy, the shadows will do whatever they want, meaning that if you get surprised around a corner by some monster you think is too strong for you alone, the shadows are ... elsewhere doing their stuff while you're taking damage.
Sure once you get the shadow focus skill that is better, but until you able to get it, boring.
Now the damage dealing stuff. Basically you do weak damage with your spells even maxed, and to add insult to injury, all your spells have very low range.
So despite you're not a though class you're basically forced to always get at 3 or 4 tiles from a dangerous enemy (so they will have no problem to shoot at you then) if you hope to deal a bit of damage, additionally you need to keep them on sight so your skil increasing your hate will work instead of constantly decrease.
Fortunately it gets better once you get the Blast power (but it's still damned low range) as it's basically the only serious damage spell you have (it's AOE fortunately so it can help cleaning rooms) but until then, damage will be really weak.
So basically, early game is tedious, boring and not fun, it apparently only get better later but keeping my interest until then was simply impossible.