An ambitious attempt to take the series in a new direction crippled by the fact that the direction in question turns out to be 'down the drain'. Shoddy design and construction across the board leave this one without a leg to stand on.
A poorly-designed outing that might, in another continuity where the previous Thief games never existed, have earned itself the heady accolade of 'barely average'. Unfortunately, we all know that it could be - and has been done - so much better.
The inevitable result of a collision between ambition and inexperience. Not recommended unless you feel that Terraria would have been improved by the addition of a cling-film-thick story, airship combat, and a heavy sprinkling of bugs.