We are a household of 3 and owned the NuWave previously. Many have left good reviews of this machine already, so I will focus how it the two machines compare.
After 9 months, our Nuwave see-thru plastic shell cracked. Even before the cracking, it became opaque like an worn plastic car headlight. The white plastic base was already yellowing as well. The Nuwave was still functional, but it was too big and got uglier by the day. The heating unit on top was very sturdy and of a resistor design similiar to most conventional electric stovetops - it probably wouldn't break for a decade.
On the other hand, the Secura Digital (SD) has a glass body shell which I greatly prefer. I don't think it is tempered, which means one shouldn't put it in cold water while hot or it may crack. Otherwise, it's a much cleaner and better design. The heating unit is halogen, like the 500w utilitarian work lights around. Halogen lights seem prone to breaking, but our oven is still is in one piece after 3 months of extensive use. Should the heating lamp break, it can be replaced for $35 and seems like a simple procedure to replace. It's rated for 2000 or 3000 hours, I believe, and the filament seems thicker (and hopefully sturdier) than said worklights.
The Nuwave has 4 big pieces to clean. The clear plastic shell covered in splatter, the gray metal drip pan, the white base (which always has meat juices in it after use, for some reason), and the metal rack. All these pieces are large, they will hog all the room of the bottom rack of a dishwasher.
The SD has 2 medium-large pieces to clean - the bottom glass shell and the metal rack. The glass shell can fit in the bottom of a dishwasher with much room to spare for dishes, and the metal rack can fit in the middle rack of a dishwasher. The glass cleans easily and still sparkles like new. There is a 3rd piece, the glass on top, but a quick sponging suffices as it hardly gets dirty enough to warrant disassembling it (if even possible).
In operation, the Nuwave cooks okay at the medium-high to low temperature ranges. It seals the air in and keeps things moist. It has a bigger body and probably can cook bigger things. I have not tried a goose with it, although I believe it might fit in this one, defitely not in the SD. If you wanted to turn meat over or add things, you have to take the heating unit off and clear plastic shell off (the top) and have a large, free space beside the machine for the top.
The SD also seals air in and cooks excellently. It gets hot faster, and has a high to low temperature range. The halogen can get really hot and give Chicken a nice crisper skin than the Nuwave. In the normal configuration, it can cook a large chicken. With the extender ring, we have successfully cooked a duck, which has an elongated body in comparison and needed to be slanted. A goose, otoh, is too big and I had to opt for the normal oven. This higher-end model has a swing arm connected to the top. It's very convenient to just flip it and meddle with the food quickly.
The display on both (digital versions) are okay and easy to use, although I think the temperature and airflow guage text are too small on the SD digital for older eyes. Eventually you'll learn the position of the LED lights to not need the guidance of the text, but it should still be bigger. The cooking time on both are easy to read and adjust. On the SD, you can adjust airflow from Hi-Med-Low which is a feature not available on the Nuwave IIRC.
A complaint I have on both machines is that the chrome on the metal racks have given way to copper underneath. They were very thinly plated, perhaps flash plated. They should have been better quality.
I knocked a star off the SD for the display and metal rack plating issues, but otherwise love it. It's superior to the NuWave as the daily appliance, it takes up significantly less space but it doesn't feel like I'm need to cook smaller portions. It's aesthically more pleasing, plus easier to clean. I'm glad I went with the digital version for the more precise control and swing arm. The extender ring is useful too. Another nice touch of the SD is that it can be truly turned off without be unplugged. It has an old fashioned power switch on the side, and not merely a "soft" off that sets the machine dozing at a few watts an hour. More and more devices are missing that these days and playing energy vampire while not in use and it does add to the electric bill with an entire household of gadgets behaving this way. Just thought I would mention that.
Bigger households may want to explore a bigger machine but I can't see why it couldn't service 4-6. It also toasts bigger bread pieces nicely in minutes:) One thing to be aware of with any machines of this nature is that it cannot cook pizza well - pizza needs to be heat from the bottom, otherwise the cheese is burnt and tomato sauce is boiling, and the crust can still be frozen. A conventional oven is better for that.
To sum up:
Space Winner - Secura. Less countertop footprint while having just a wee less cooking space.
Heating Element Longevity - Nuwave. Uses a resistive heating coil like many stovetops do. Secura is a halogen bulb, notorious for burning out. On the plus, the bulb gets hotter and can crisp chicken skin and fries at the high heat setting.
Clean up - Secura. Made of glass, easier cleanup. Less parts. Sized to fit in dishwasher. Many Nuwave parts won't fit. Buttons on secura covered by plastic sheet, so there are no spaces for gunk to accumulate.
Body - Secura. Made of glass. Nuwave plastic fades and becomes opaque like a cheap car headlight within a year of use.
EDIT: October 2012
We finally had to replace the bulb as it burnt out. We used the machine a fair amount, cooked a lot of chickens, but I would say we used it 500 hours and not the 2000-3000 hours bulb life the company claims. I found a new bulb through ebay, same manufacturer, for $25. Unfortunately, what I thought would be a 15 minute affair, turned into a 3 hour one. Without instructions, my son had to grapple how to disassemble the machine to replace the bulb. It's not a simple plug & play affair, unfortunately. You have to remove the 3 cover screws and take the cover off. After that, it becomes less straightforward - as there are over a dozen screws, as well as the fan. The answer is to remove the 4 deeply inset screws (that are in the circular enclosures) and to keep turning until they come out. I'm sure next time it will take only a half hour. Some of the internal pieces like screws looked sufficiently rusted that I suppose we can replace the bulbs 2 or 3 times max before it becomes a good idea to replace the machine with a new one.