Probably not...I myself have never bought it, but I hear it's pretty useless. You can use teddy bears and random junk to launch at enemies and the like....
However, I do plan on purchasing the schematics for it now because one of the trophies is to create/make every type of weapon in the game. So, I guess it all depends on what you want to do, but on my first play through, I would highly advise to save those caps for something more worth your money, like buying any needed ammunition or holding off to repair needed attire or weapons if you can not do it yourself at times, etc.
Never used it other than for fun. Only reason to get the schematic is so you can get the trophy IMO. I wouldn't waste caps on buying it early on if you don't have a ton. It just doesn't do too much damage in my experience, and regular weapons are better. Plus that damn thing requires you to carry a bunhc of junk around so you use up weight you could be using for stuff you actually need, or want to sell.
A.I. to Detroit=NBA Title=Lebron in 2010 http://img.photobucket.com/albums/v643/ripvanwallace/confusedpete.jpg
I bought the plans when i was making all the various created weapons, and early on if you're having ammo troubles it's nice to be able to grab all the clipboards, coffee cups/pots, and empty nuka cola bottles in the world to shoot at people.
In terms of power it seemed to be *about* as powerful as the hunting rifle, but without the really annoying bolt action.(this would of course vary depending on your big guns and small guns skill levels, mine were close but small guns was slightly ahead.
However the major downside to it is the durability is AWFUL. Almost seems like you can watch the durability of it steadily drop while you're firing. also having to dedicate 20-40 lbs in your pack to ammo sucks too(loading it into the gun doesn't take it out of your pack, apparrently)
^^The power depends on how many schematics you have and your Big Guns skill. If you have 100 Big Guns or all the schematics then it'll max at 50.
You're right. I suppose that I should've looked it up before saying what I did. So, here is my correction to my earlier post.
I personally feel that the rock-it launcher is only worth using as a joke weapon. That is not to say that it is worthless or weak. But as far as efficiency goes, it is more than likely to become a hindrance rather than a benefit. Use it if you'd like, or not. That's your decision to make, and not mine.