Gary,
I used to be into photography rather heavy about 15 years ago. I used all Canon equipment, and developed my own film in a dark room. With the many changes (lack of film, equipment, etc) and advent of digital, I kind of lost interest. Now that the manufacturers have had a good few years to develop upon digital technology, I've decided to get back into it. The Nikon D5100 is not mirror-less, rather a pretty solid DSLR camera. Not sure I would want to jump into the new mirror-less technology quite yet. I'd rather give it a few more years... I prefer the more traditional technology.
My next camera will be along the lines of a Nikon D7000. I figure I might as well get back into it with something decent, yet not too low end. The D5100 seems to fit exactly what I'm looking for. Like anything else, it's the photographer who makes the photo. A good photographer can use a cheap camera and come out with award winning prints.
From the many reviews I've read, Canon is still a top performer. Nikon has a very slight edge, at least when comparing the T3i to the D5100. I'm more concerned about photo quality rather than video quality. Canon also seems to be a bit higher on the contrast side, where Nikon shoots prints just a tad darker. Apparently the color quality is more true to life on the D5100. Who knows, it's like comparing Padron to Padron, very similar.
I'd rather my photo's come out darker than lighter. They say the D5100 is not so good for shooting with low light, however I can combat that by switching to full manual mode and adjusting the ISO and SS accordingly.
My focus will be landscape/outdoor scenes, along with night sky photography. I will need to get some add-on's so that I can take 30+ second exposures.
I was able to get the D5100 for $746 (regular $899), and a 55mm-300mm lens for $246 (regular $396), and a few other add-on's really cheap from B&H in NY. They by far have the best prices; I've bought from them before. Free shipping and no tax. They're the only one offering the additional Nikkor lens that cheap. I can sell it and easily make $100, and put the profit towards an even higher quality telephoto. That special ends in a day or so.
I've been researching DSLR's for the past six months, so if you need the cliff notes on anything just let me know.
You really can't go wrong with either Canon or Nikon, just depends what your goals are. They both have slight advantages over one another, however are both leaders. They're the only two brands I would consider when it comes to photography equipment.
My equipment arrives next week!