i bought it, I'd like it more if I wasn't so confused. Maybe we can attribute that to not reading the manual.

You probably can. Giants takes a bit of adjusting, although I don't think the learning curve is too steep. Now, depending on how far you've actually gotten, I assume you've at least laughed yourself silly a few times already, no?

I can't catch all the falling smarties. :(

You're not supposed to wait for them to fall. You're supposed to fly up and get them, one by one, and drop them off at the smartie pad on the small island next to the circle of stones. You do know you have a jetpack, yes?
[EDIT]
Tell me you've at least looked at the keyboard configuration! ;-p

Have a look at this, maybe it'll be of help.

You can fly forward or fly upwards with your jetpack, depending if you are running or not. if you dint stood still before using the jetpack you wont get much height. No sense to "change your course" in mid-air, rather land ASAP and try again.
Controls are pretty unforgiving in this game, especially if you dropped of cliffs (or missed landing n them) you have to do a fair share of backtracking.

I felt like the building levels were entirely superfluous and just amounted to nothing more than a lot of meaningless busy work. Plus Kabuto levels were surprisingly monotonous but everything in between is pure satiric gold!

I bought it a couple of hours ago and I'm loving it. Having some great laughs with it and the gameplay is awesome.

I suppose you could call it a run-n-gun game at its heart but it really is unlike anything else and the humor is brilliant.
If its anything to go by I bought it from GOG even though the CDs are within 2m of this computer.