I'm no expert paddler, but not a complete novice either. We bought/got our Nahanni as a wedding gift. It's absolutely gorgeous with cherry/ash gunnels. I also love its weight (or lack of). I'm a big guy (6'7", 210#), but portaging this canoe is a breeze for anyone.
Unfortunately, we never felt completely comfortable with the canoe. It feels extremely tippy and we're always nervous with the kids in the boat. A friend of mine who is a hardcore WW paddler took it out for a spin on the Ottawa River and he too had a very tough time getting a handle on it. I tried soloing once and it was a nightmare. My wife, a more experienced paddler, fared only marginally better.
I paddled a Nahanni for about a week. The boat I used had all wood trim with a two tone paint job, and it was quite a head turner.
On the water the Nahanni is a rocket. Definitely faster then some tripping canoes a foot longer. It was also possible to turn it, although I would say tracking was this boats strong point. Paddled tandem, it's initial stability can make it feel tippy at first, but I found the feeling to be short lived. Take solace in the fact that you're probably not going for a swim, as it's secondary stability is very good. I was able to paddle (solo) with the gunnel skimming the water, And could easily dip it under the water and still pull back up.
Paddled solo, the Nahanni performed nicely. The canoe I was using had a kneeling thwart and pads, which were very comfortable. The boat retained the same characteristics as when paddled tandem, and with a little bit of a heel, becomes more maneuverable. It's not a pure sit and switch solo, so you do need to reach a bit on your stoke, and outside of leaning it way over, you won't get a perfectly vertical paddle. But you can't very well fit two people in a Prism, and as a combo tandem/solo flatwater boat the Nahanni seems like a strong option.
Rating: 9/10 - because my girlfriend says it's real pretty
The Nahanni is the best boat I've ever owned. It is a dream to solo, so stable you can literally drop the gunwhale right under the water without tipping. This boat has stood up to the abuse of the entire family, it's scratched, but otherwise completely in tact.
I also own a Swift Kipawa, but it seemingly gets very little use now. I would recommend the Langford boats for cottage, lake, river, & tripping. I also have an ABS Old Town Prospector with wooden gunwhales, a boat to abuse, 'cause the Nahanni is just so darn pretty.