I wouldn't class this as a good or bad film, it's in a weird sorta in-between to me.
'The Chronicles of Narnia: The Voyage of the Dawn Treader' is, comparatively, bad. It loses the vibe and all the intrigue that the first film has, as it continues the downward trajectory set by the other sequel. However, it's still just about got a decent adventure feel to it.
Only two of the youngsters reprise their roles 'properly', those being Georgie Henley (Lucy) and Skandar Keynes (Edmund). I'd always prefer a cast to remain the same, but if I'm honest this doesn't miss William Moseley (Peter) and Anna Popplewell (Susan) all that much. That argument is helped by the arrival of a young Will Poulter as Eustace. He's great.
Plot-wise is where it gets meh. I didn't care for it, even if I did like its swashbuckling nature. I can see many finding enjoyment with it, but for me it doesn't quite come out positively unfortunately - it's sluggish. The ship set also feels rather cheap.
Not at all a bad film; one that was interestingly made without the involvement of Disney, Walden Media joined up with Fox instead. I just couldn't find enough entertainment in it.