This really is an excellent kayak, which works well either as a one- or two-person boat. It's easy to carry either in its bag or fully inflated, quick to set up, and simple to pack away. Once it's deflated (which is very fast) and dried off, it folds to fit in the bag easily and with plenty of room to spare. I had no trouble with any part of this as a solo user.
On the water, the boat is much more stable than one might expect, and it makes a decent speed if required. I found that the skeg makes a huge difference in achieving directional stability: without it, the boat was surprisingly susceptible to currents and wind. With the skeg fitted, it kept nice and straight, yet I had no difficulty turning tightly when required, even solo.
With two on board, there's room to take enough kit for a comfortable day trip if one makes use of the bungee cords on the decks. With only one person though, deck space is plentiful, and the boat still handles with ease: this is probably how I'll use it most often. I'm glad I chose the two-person Optimal over the one-or two-person Explorer.
Build quality seems excellent. I've found a small amount of wear on the bottom of the bag after a few trips and a D-ring on one of the packing-away straps snapped, but I count these as pretty inconsequential. I think the seats are comfortable and I've no complaints with the paddles, though I can see that they'll start to move as usage wears the fittings. I've made a footrest for single paddling: basically a length of hose inside a foam pool noodle. One of the straps will hold it in place through existing D-rings on the boat.
While the pump that's been supplied works pretty well, it's slow, hard work to inflate the boat fully. An electric pump makes a big difference - but it might be difficult to find one with a big enough battery to inflate two decks to 10-12PSI.
Overall, this is a first class boat and I'm very pleased with it indeed. Buy one and enjoy the freedom of paddling when and where you like without being restricted to hiring!