We've owned a Tandem for around nine years now, and have been very impressed by its versatility. I've used it in a wide range of sea conditions, on rivers and lakes, and while it is not a fast boat, it has handled all but the most extreme situations well. It's excellent for fishing and diving (I use mine free diving or spearfishing). We also have taken it on 3-4 day wilderness trips, and it's surprising how much can fit inside the hull. We got a large rectangular hatch to get things in more easily, but very little water leaks in.
It works fine when paddled solo, but you sit quite high. IMHO, it performs much better with two people in it, and perhaps a bit of weight in the hull. It's taken quite a few beatings over the years, but the effect seems only to be cosmetic, and it continues to perform as well as it did when we bought it. Virtually no maintenance - I'll hose it down, particularly the metal parts on the hatch covers, after sea paddles.
Overall, the Tandem might not be slickest boat out there, nor the fastest, but if you're after a kayak with a range of purposes in mind, then you'd do well with this.
I paddled a Cobra Tandem for two years and had no problems with the quality of the boat. Finish, durability of the boat is great. Very good storage compartments and the boat is easily handled out of the water. Plastic boats can take a bit of a beating.
This boat is very flexible, can be paddled tandem or solo with an easy shift of the seat latches. This boat is good for day triping around the harbor and extremely stable. Did I mention that the boat boat is also very stable.
My only gripe is the tracking, the boat tends to zig zag a bit and requires good paddling skills and some coordination between the front and back paddler to keep straight. If the boat were 2 feet longer, it would be a pretty fast sit on top.
For a plastic boat the cobra Tandem is great for beginners and leisure paddles. I used it for adventure racing, but have moved on to much faster fiberglass boats.
I was considering buying Ocean's Malibu Two, for I though Cobra's higher price was not justified. After trying them side by side, there's no comparison. Cobra beats Ocean by a mile. It's much more comfortable, more stable and has a nicer finish. After a few minutes on the Malibu, my legs were cramped and I had to get off to stretch. Also Cobra's powerflex paddles are WOW! very comfortable and feel great. Oceans' paddles hurt my hands and let you advance very slowly. I wish Cobra made a touring tandem!