Spelljammer hands down is my favorite campaign setting ever produced, silly bits and all.
It's a setting that has so much potential and one that isn't really set up for a novice GM to run. It's a very sandbox kind of setting that I think needs a GM who is comfortable at running on the fly. It's also best IMO if you divorce it from the big 3 (FR, Greyhawk, & DL) as much as possible. Start out in them if you must but quickly get away and work on building your own spelljamming society built around all the nifty hooks scattered around the setting, with the Rock of Bral as the center point. I didn't mind the goofy elements so much, but then again I didn't dwell on them or just ignored the ones I didn't like, for example, giant space hamsters powering ships.
Some of my favorite hooks:
The vodoni war,
The showdown between the scro and EIN (elven imperial navy)
The illithiad trying to darken spheres
The tenth pit slaving operations
The merchant houses trying to out do each other
The political machinations of the EIN, who can make for some pretty nasty bad guys in their own right.
The last is more of my take on certain factions of the EIN, who can be kind of fascist and hardcore especially if you start having the scro kicking their ass. The kind of group for who the end justifies the means, and the players have to help excise this cancer from the EIN.
All in all a great setting if you like the space fantasy mash up.
I love the Giff too!
"Maybe I can't be a paladin and carry a holy sword, but I can still use 'Lady Elaine' here and get exactly the same results." - Major-General Ruthgar Gronig, Company of the Chalice said while fondly patting his three-barrel arquebus nicknamed 'Lady Elaine'