The all-or-nothing saving throw may make this seem like a less useful effect than Chromatic Orb, which has the chance to deliver Critical Hits. What many miss is that the projectile only stops when it hits something. If you catapult an object at more than one creature in a line, the first target passing their save just means the second target now has to roll a saving throw as well.

Agreed. Plus, magical bludgeoning damage is almost impossible to resist, while certain monsters (ghosts, shadows, slaad, demons) resist all of the elements in Chromatic Orb. Also, monsters with high AC tend to have low Dexterity saves (and vice-versa), so having a save-based spell is a good idea.

I just LOVE throwing rocks at stuff. ITS SO MUCH FUN

Had a silly moment where our Sorcerer felt he was being unfairly disadvantaged, the area was very empty and he didn't have anything to Catapult, the room was void of small objects but there were some very large crates and stuff, much too heavy, so as an action he threw up his dagger and then Quick Spelled this as a Bonus Action. GM thought it was a neat, so he even changed the damage type to piercing for that instance. The spell straight up killed his target and then after he Catapulted the dead guy's short sword into another enemy. The whole thing was quite comical.

FYI:
An object traveling 90 ft in at most 6 seconds is traveling at least 10mph.
Weights for common objects can be found in the Equipment chapter of the Player's Handbook.

Is it like lightning bolt effecting every creature in that 90 foot line or the first person it hits? 

Quote from Owen817 >>

Is it like lightning bolt effecting every creature in that 90 foot line or the first person it hits? 

 Just the first person it hits

My wife uses this to launch her grappling hook on her eldritch knight. There is something kind of amazing to have the Dragonborn just leap off of buildings or vehicles like Batman.

Had anyone thought to combo this spell with [Melf’s Minute Meteors]? 

If a minute meteor has a weight of 1 pound than it may be used.

Quote from Shevara >>

My wife uses this to launch her grappling hook on her eldritch knight. There is something kind of amazing to have the Dragonborn just leap off of buildings or vehicles like Batman.

 I'm stealing this

Does any one else find this to be a bit overpowered early in the game? It's kind of driving me insane as a dm

A good fix for the issue of its early game potency is to throw threats at the party that encourage them to use the relevant spell slots differently or before the main encounter of your dungeon, my game had a dps specialist sorc and our gm handled his stunning dps by creating longer encounters to force him to ration and pick his moments better, give it a try might help. 

Combine with a bag of ball bearings to make a shotgun

Im using this for my alchemist (transmutation wizard). being able to launch an Alchemist's Fire is fun, also it counts as transmutation spell witch is useful when you get your Transmuter's Stone.

There are two things about this spell which are slightly unclear to me:

(1) Is this *magical* bludgeoning damage? Seems like yes, but it also seems like the force of the throw is what's magical, not the object doing the striking. Therefore, it also makes sense that a rock which is thrown by magic is just the same as a plain old rock when it strikes its target.

(2) Does a creature with special magical resistances (e.g. a marilith) get to apply them here? Or is it just a rock coming towards them at that point? Again, is it resisting magic, or is it resisting a rock?

My feeling is that both of these questions should have the same answer (since it's either a magical effect or just a rock that was thrown by magic), but I'm having a really hard time resolving this mentally.

The main Range and the Range in the spell description differ (60/90). I've been using 90, but this might confuse people!

Quote from onlySLIGHTLYclever >>

The main Range and the Range in the spell description differ (60/90). I've been using 90, but this might confuse people!

Spell Range: 60ft
-Target: "Choose an object weighing 1-5 lbs within the range"
-Effect: "It flies up to 90 feet in a straight line, in the direction of your choice"

The initial object you target must be within 60ft of you, then you can choose it's direction and it flies up to 90 feet (or until it hits something)

Hope that clears it up for you ^^

I have to ask, because this might make the spell that much more interesting; If you have a five pound object, send it 90 ft upwards above the target, and let it drop, does it still only do 3d8 Bludgeoning (and I'm not sure if it would be "magical" damage like some people are saying) or would it deal damage based on "fall damage" from coming down?

 ...

Ok, I've dome some minor research, and the fall damage rule for objects is that it must be 70 ft or higher up before an object that is 1-5 pounds - the starting weight of the spell - can deal 1d6 Bludgeoning Damage, with another 1d6 being added for every additional 10ft, to a maximum of 20d6. This doesn't seam like a viable option until I re-read NordicNinjas comment:

Quote from NordicNinja >>

FYI:
An object traveling 90 ft in at most 6 seconds is traveling at least 10mph.
Weights for common objects can be found in the Equipment chapter of the Player's Handbook.

Here's the thing though; that five-pound-rock is STILL moving after its initial push of 90 ft, as it hasn't HIT anything yet from going straight UP. The question then becomes this: After the initial 90 ft that we get for free thanks to Catapult, how far will said object go NOW, traveling at roughly 10 miles-per-hour until gravity catches up to it once again?

The spell itself does 3d8 Bludgeoning, for a max of 24 damage. So, if the rock that is launched straight up needs 70ft of DOWN to gain 1d6, that sounds like a net loss, BUT so long as the rock continues from the 90 ft - which means it's now at 3d6. (70 ft minimum plus 20 ft to reach 90 ft) that's only 18 MAX damage, but that's only if the rock stops AT 90 ft. So long as it can reach 100 ft, only 10 more feet, it's MAX damage will match that of Catapults at 24. (70 ft is 1d6, 90 ft is 3d6 so 100 ft is 4d6) That should be easy for an object moving at 10 mph, even if it's initial momentum - the spell - is no longer acting on it, as the energy to move the rock is still there. Unless the spell just causes the object to STOP moving AT ALL after 90 ft, then it should continue upward for...I don't know, that's more complicated than I can do, but I think the rock MIGHT have enough leftover energy to POSSIBLY be able to reach at least 120 to 130 ft up. If it does go 130 ft up, and THEN starts falling, it'd hit with a Fall Damage Dice Pool of 7d6, for a Max Damage of 42!

Finally, just for fun, if you use a 9th Level Spell Slot on Catapult, that means you can use an object that is 9 X 5 + 5 pounds, or 50 pounds. That still only travels 90ft, but does increase the damage to 9d8 (1d8 plus 8 levels above 1st level spell slot) for a Max Damage of 72 Bludgeoning Damage. The Falling Damage Rules though state that an object that is 50 pounds only needs 40 ft to start dealing damage. 40 ft min. is 1d6, plus 60 ft to reach 90 ft makes it 7d6 - the last max possible using fall damage -  and at 130 - my best case scenario guess -  it's 10d6, a Max Damage of..60 Bludgeoning Damage...ok, there's a bit of fall off (heh) but it's still an interesting idea. 

I also realize that I might have answered my own question, but I'm no math savvy, so I'd like some help with the numbers, even just to check my work.

Well it says straight line rather than arc before dropping so that would suggest energy is supplied to the entire journey.