Sorry, fairly late to this set now I am out of my "Dark Age", but unfortunately it feels like less than the sum of its parts to me as well. There should be so much to like: classic spacemen, printed pieces, a reasonable price, and clearly a lot of thought and care went into the design.
However, as many have commented, it is too big and fragile for effective "swooshability". OK, it is a marketed as an adult set but surely many will want to enjoy the set with children. It is such a big flaw.
While some of the building techniques are interesting (the slanted double cockpit, the arrows, the cargo door mechanism), they also feel over engineered to me; complicated and big for the sake of being complicated and big rather than adding to the form and function of the set. I actually prefer the alternate models. Some of the interior details like the airlock are well done though.
The biggest drawback for me is that it doesn't feel like "Classic Space". While it is hard to define, there is something practical but idealistic about most of the original designs. They appeared designed for scientific endeavour and exploration (and to be played with!!), rather than to necessarily look sleek and streamlined like the new Galaxy Explorer, to some extent I am sure due to limitations in parts and cost. The new set does feel soulless in comparison.
I accept this will seem like nitpicking. I think it demonstrates how difficult it is to recreate old sets. Too faithful and it is hardly worth doing; too many changes and you risk losing whatever it was you were trying to recreate.