There are some very good points and some considerably less good points to note about G P Taylor's Tersias.
On the upside, it's a pretty thrilling, well plotted tale, with plenty of twists and turns. Switching between locations for each chapter creates a filmic effect, with lots of cliffhangers. The writing is vivid and intense, and the characters are well drawn. It's highly original and imaginative.
On the downside, rather like Shadowmancer, there are too many different baddies and monsters, and no clear sense of an ultimate uber-foe. None of the protagonists are particularly sympathetic (this may be a strength for some; it's not for me. I found them all quite repulsive, and rather hoped they would all die). It's good that he's working with "new" monsters, such as the Wretchkin, but a new mythos perhaps needs to be better established. There are too many different ghouls and spirits - the wolf, the Wretchkin(s?), random spirits, white wavering hand, far too many glowing red eyes and fangs and things creeping in and appearing and being remembered from childhood. Admittedly I tend to read things a bit too quickly, being impatient for the ending, but I got confused.
Having two protagonists whose names both start Mal- is not a great idea. It creates a strange sense of echo or confusion, at least in my head. "Magnus Malachi" is a superb name, but "Malpas" could easily have been changed to Valpas or something.
Then this one is a matter of taste, but many readers might find Taylor too graphic and too gruesome. I would be wary of buying this for more delicate little flowers, it's considerably stronger stuff than Harry Potter. The way Taylor recreates a sense of the grime and filth and violence and squalor of Old London is brilliant, but it also might make you feel rather sick.
I liked the sense of redemption that Malachi undergoes, albeit unbelievably rapidly. I wanted more on Tersias, he seemed to fade into obscurity towards the end. And I would have been quite happy for them to have fed Tara to the locusts.