This is a fun adventure movie. Just... a whole lot of old-fashioned swashbuckling fun. There's good guys, there's bad guys, there's dashing heroics, a damsel in distress... everything you'd expect from a movie like this. The production design is rather gorgeous as well - there's a reason the Rocketeer suit has become a pop culture icon.
That being said, it is, in its way, very 90s - especially the soundtrack is rather generic 90s kitsch, relying heavily on piano and strings and lacking a bit of punch. There's an awful lot of soaring, but not enough action in the music.
Of course it's all worth it to see (SPOILERS FOLLOW) Timothy Dalton act like a dirty Nazi spy.