This boat is designed for people who need something easy to store and/or transport. I wanted something I could chuck in the back of the car and be on the water pretty quickly and also something that could go on/in a VW camper. The Yakka straps nicely to the bike rack on the camper and fits in the car with a seat folded flat. It sets up in a few minutes and if paddled without accessories is really quick to get from car to water (including unfolding and pumping up its still quicker than unstrapping a SOT from the roof and fitting seats etc). So off the water it does what its meant to. I find it OK to paddle without extra seats etc.
On the water its surprisingly fast. It's not a Sea Kayak but it's definitely quick and straighter to paddle than you'd expect. I paddled it on a club trip and everyone was surprised how quick it was. Older reviews about water coming in the joint don't seem to apply now as the ride is pretty much bone dry. Due to the inflatable sides its almost like a mini canadian-canoe really. The inflatable bit is out of the water so even if it pops mid trip you'll stay afloat.
Criticisms- no rivets to attach thigh straps to and it really needs them, after 4 uses one of the hinge screws broke but on the plus side BIC sent me (via the retailer) a new boat within a week so customer service excellent. The inflatable sides shrink when they cool so come a bit loose and may need pumping mid trip. Not a huge problem but you look a bit nuts doing it in the middle of the sea. Due to lack of thigh straps its not easy to keep stable in surf/chop, however its easy to re-enter in water.
So in summary: the Yakka 120 has some great points and some weaknesses. It needs pretty careful handling when folding/unfolding. Mainly for flat water use I'd say or in a very slight sea would be fine (I use it for lazy rivers and sea fishing). There's nothing on the market like it or in that price range for folders. If it suits your transport needs get one and you'll be pleased with it, but wouldn't be my first choice of SOT otherwise, which to be fair is what its made for! Overall a great but slightly flawed niche product.