I will have to admit that I was quite skeptical when I read about your pallet/wall paneling plans. Well Sir, I should not have had any concerns because you met the challenge very well.
It's a whole lotta work and a slow go, but it sure looks good. And made a world of difference for sound deadening coupled with R-13 insulation, too. Most of it's hardwood (oak, sweetgum, poplar, and whatever else they make pallets out of), but there's some pine mixed in too. I'm leaving them outside to weather as much as possible before I put them up. After I get it done, I may mix some used motor oil with diesel and spray the entire inside walls just to make it aromatic enough to keep creepy crawlies out. Had a rather vicious 2" long centipede come crawling out from under some of the wood that I haven't pulled the nails out of yet. Not a critter you want to bite you.
I made a pallet buster to help speed up tearing down the pallets. If I had that to do again, I'd angle the fork on it just a little bit more so I don't have to bend over quite as far. But a handle made from 1" black pipe makes it nice and heavy to help with the force needed to pull the slats off the framing. If I wet them first, I seem to get a better yield from the slats and don't split as many of them. Pretty much, I'm chopping up all the spacers for stove wood. The framing is too thick for what I need, and have too many nails to try to re-purpose. I got a bunch of used pallets from my step-son, and those have nearly double the work in them getting all the little sawed off nails out of them. The advantage with them is that they have wider slats generally speaking. But the single use pallets I got from my son-in-law are all thicker hardwood and a LOT easier to disassemble because there's fewer nails and they're not corroded as bad.
I thought about getting a pneumatic nail remover, but I'm right at 75% complete now. Got nearly half way up the 3rd section of the back wall today. Not much point in getting something that will spend most of it's time laying in a drawer. Same reason I didn't switch to a brad nailer. I just got the smallest nails I could find for the framing nailer. It'll take any brand nails on any angle, so I can't complain at all about a cheap Harbor Freight nailer ($109 on sale plus another 10% Inside Track Club discount when I bought it). I've probably gone through 20000 nails with it, and VERY few jams. One was my fault completely (misadjusted the magazine) and another was because I hit a screw head under where I was putting the nail. It balled that nail up pretty good, and three more came out with it pretty much shaped like spaghetti. That was a frightening experience, and I still haven't figured out how that many nails came out with a single discharge.
One thing I've learned is how much easier it is if I go ahead and trim/edge both edges of every slat to a common width. I also pre-cut everything to 48 (standard pallet width), 32, and 16 inch pieces which makes putting it up go a lot faster. I've probably made at least 300 pounds of saw dust in the past few weeks. The only pieces I have to custom fit are at the corners or where I stitch the wall sections together, otherwise, they all fit on the 16" stud centers. I actually had a goal of it looking somewhat jinky, and I'm hitting that one outta the park. I kinda want to go get 5 sheets of plywood and cover either side of the East window like I did the west end, just for symmetry. The Missus wants me to keep going with the pallets. Easier said than done, but not impossible. Like I said, it's a lotta work, and something I'll never get my labor investment back from. Overall, though, I'm figuring it'll run the property value up about $20-30 K. What I'm doing with the tractor will add at least that much more, and give me plenty to do to keep outta the Missus' hair when I officially retire.