The following file types are supported:
1) It is free (run by the Canadian gov't and the US NSF)
2) you can download a WCS solved image
3) it's fast - they advertise return of the solution within 10 minutes, but I find it to be much faster - like 45 seconds
4) you don't have to tell it where in the sky you are looking (if you do, it is ignored)
5) You get the plate scale (arc sec per pixel) and dimensions of the image (x arc min wide, y arc min height
6) Raw images are just fine (no need to dark subtract or flat field)
1) There are limits on the size of input: the image must be larger than 0.1 degree and smaller than 180 degrees.
2) The service isn't always available - only about 95% - 98% up time.
Here's a small section of the output for an image I sent in:
Lewis M. Cook (Lew)