I recently purchased this Sigma 18-250mm f/3.5-6.3 DC Macro OS (Optical Stabilizer) HSM lens for a trip to Yellowstone. I could not find a lens sample thread on it, so I thought I would start one.
My simple review... first, its not a prime, nor it is a short zoom. So yes, there may be issues at times, that are common among all super zooms. This is acknowledged and accepted to some extent. The thread isn't what this lens is not, but what it is.
However if you need to manage your complexity or volume of gear, this lens fits a great spot. In my case, my primary lens is the Sigma 150-500. However, with that beast of a lens, I found that I needed a landscape lens, a family lens, and just as important, a sit on the seat next to me for the quick shot lens. Remember that any shot is better than a missed shot.
There were several times in Yellowstone where I went from 18mm landscape, then saw an animal and went to 250mm and then back again. Not having to change lenses in this circumstance was wonderful. I travel with the family and the kids. They don't want to stop and wait while I change lenses constantly. I used to have a 18-85 and a 55-250. Both were good at what they did, but I found that too often I would skip a potential shot because I had either left the other lens in the car, or simply didn't want to make a quick lens change for that one shot. This lens is also very small. At only a couple inches long, it is very easy to carry. Would imagine it would make a good all around lens on a Rebel or SL1 even. It seems a little tiny on my gripped 7d, but it is still very comfortable to use.
I will post more... if you have any shots, feel free to add them to this thread.
These were edited in lightroom... but that is how I shoot, so that is the best way to see what this lens can do.