Briefly: Plot is good but executed ok-ish; a nice tale but heavily christian, sounded like catechism. Characters are so and so, especially the main female who felt like a romantic tool for Marc.
Now the long version. The language is good, evocative but not pompous, fluid and well-honed. Good job to the author. The action scenes are brief and reasonable, mostly, and the tension is good. The pacing could be improved, tension goes down too often for too long.
What really put me off is the Christian theme so explicit. When characters continuously say "God bless you", "God bless me", "Thank God for that", while living in a kind of apocalyptic context, that seems absolutely unrealistic to me. That's when the worst gets out of people, and they might plead forgiveness to God or Gods but with fear, resentment, desperation: not with overflowing gratefulness.
Those kind of expressions are put as common sayings, yes, but are also present in the introspective bits of all main characters. It sounds to me like the author's belief system got too involved in the tale, at the expense of internal coherence.
There is also another thing that needs work: character development.
Marc is too scared/afraid of magic, unreasonably so since he greatly respects the wizard Oren. Now, either he shouldn't be so afraid, or he should not respect Oren so much. There needs to be a reconciliation between these two, but I didn't see it. Yes, later this changes under Oren's tutelage, but I find the "premise" unrealistic.
Valeria is a bit stereotyped, and she kind of acts like Marc's support only. She dearly loves him, she helps him out, she quench his fears. She's a mother-wife before being even romantically involved with him. I prefer strong, well characterised women in my fiction.
To conclude, I think the author has potential and the next novels will probably be stronger. However, I doubt I'll be buying the sequel of this. Not my cup of tea.