All the power lies in the Subclasses, which are very interesting, but the first two level are extremely weak. On the first level his only special Ability is a non-combat situational one, while only having mediocre stats (same as cleric but without having spellcasting). At second level he gets the magic-weapon feature which seems quite nice, but the drawback is unnecessary in my Opinion.
But he looks quite nice after that, and as soon as he gets to 5th Level, with his second Attack and the damage boosts he really starts to become a interesting Striker. I think the caster-subclass is a bit weak, since it mimics the Eldritch Knight, but without the very strong Base-Class Features of the Fighter (HP, AC, up to 4 Attacks,...) and the Mutant Sub-Class is extremely cool but changing Attributes in mid-game sound annoying (hated that in 3.x).
Overall I like the flavor of the class and think that if you don't worry to much about perfect balance then it is a fun class, but try to get them to 3rd Level as soon as possible (or am I missing a special feature that makes the first level good?).
