Engineer is hard because it's hard to be "useful" with him.
Alot of it comes down to really awesome timing and dispels with his shrink ray, among other things too.
As for thorn, he's just a fun noob basher for the most part
He's pretty good though not the best. After reading tons of threads it's pretty much down to Nomad and Psychopomp.
They nerfed them a bit fortunately but they're still quite strong. Like the guy says though, a lot of the bloodlines are quite close in terms of balance.
You'd think Spearmaster would suck after some good games with him, but Jackazzm would make your head spin with his Spearmaster in tournaments.
Hell possibly blood priest might be pretty decent now after buffs. Originally shat on compared to other healers and now he seems a lot more inline
There's one thing for sure, there's bloodlines that are easier to play *thorn being the biggest offender
Even then, a thorn is very easy to pick apart 1v1. 2v1 it depends and they can be quite nasty and they start to shine in their role of rooting, disrupting and tanking. Though once you dodge their stuff it becomes a LOT easier. His pull is kinda slow but very effective if it lands.