I encouraged a friend to buy an Alpacka Yak last year, and then proceeded to use it myself to try it out
About five years ago I bought an Advanced Elements Packlite, which is a "poor man's" version of the Alpacka. Even at that, I can't believe the use I've gotten out of the Packlite! It weighs 4# and fits in a file box. I keep the kayak in the "tire locker" along with the paddle (4-part take-apart), the pump, my lifejacket, and booties (plus the Ford jack, my breaker bar, torque wrench, spare belts, socket adapters, and tire patch kit). Oh, and my entry mat. Yep, it's compact. I can also be ready to go in about ten minutes, including changing shoes and etc.
I have a paddling background, and does it measure up to a "real" kayak. No way. But that's not how I use it. I use it to get out on the water with no fuss. I can easily carry it in to a mountain lake. Easy river trips. It's not fun to paddle ten miles, that's for sure. Also the Packlite is pretty marginal in waves (not that it would tip, but waves come over the side). Also it "shrinks" in cold water and there is no easy way to top it up once you've left the pump behind.
The Alpacka is *worlds* better, but sort of the same concept. It is about 6 lbs. and doesn't quite fit in a file box, but otherwise similar. But it has big tubes (water does not come over the side), a way to top up without a pump, and is just all around a more "serious" boat. Paddles better too, although you are never going to mistake it for a real (hard) boat. Basically, for me, it gets me out vs. not because I'm not going to carry a "real" boat at this time in my Chinook.
Somehow, both of these boats captured my fancy whereas the "normal" inflatables didn't (Advanced Frame, etc.). They were still super wide (I prefer to paddle narrow boats), but then weren't super light, tiny, and easy to deal with. I'm sure they do paddle better though, so it all depends on what you like. But the extreme lightness and compactness of the Packlite/Alpacka make them seem kind of otherworldly to me, and I don't compare them in the same way to a real boat. Oh, the Alpacka is also quite comfortable to just lie back and read in
The Packlite is just one boat. I wouldn't particularly recommend it unless you are fairly light and really need to keep the cost down (mine was around $250-300 back in 2013 or so). Although for that it is cool. Alpacka makes a bunch of different models - the one I have used is the Yak, which is what I would call the "basic Packraft" in the size one up from the smallest (leaves room for some gear ahead of your feet).
Neither of them would work well if you are going to paddle a long distance on flat water (where you want some speed) and/or with someone in a real boat (you'd be way back in the dust).
OTOH, I can't even count the number of mountain lakes, streams, and reservoirs I've toodled around on with mine. Would buy again (actually will be buying an Alpacka plus a better paddle this year; will carry the other one set in case a friend wants to come along).
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Almost all the boxes I see are just the sliding ones.