I think if you use it with their rangefinder, and you verify all the dope etc. it seems to be a pretty slick system. For whatever reason it doesn't seem to have really taken off at all though. There's lots of posts over the last couple years asking about it, and almost no actual user feedback. The new 6 series is supposed to have a lot of improvements but despite Sig saying it was getting shipped in December they appear to still be vaporware (this is nothing new for Sig, even they can't figure out when their stuff is coming to market).
Now is it going to be the optic for the guys taking deer at 1200m with a half dozen spotter shots.....no. First of all unless you run a kestrel with a rangefinder you won't get solutions over 800m, and you can't dial easily so at some point the resolution of the next closest dot that can illuminate is going to be too coarse. If I remember right the 3 series the dot spacing was approximately 1MOA, I think I remember hearing the 6 series is about half that.
Where I think it really could shine is for the hunter that's looking to extend to say 600-800m, where you can no longer "guess" hits. I know Frank hates it, but I've killed a lot of animals with a 30-06 with a 4" high zero at 100 and stays in the kill zone from 50m to 350m on mule deer, 400 top of the back, dead every time, and nothing is faster and simpler. However, after 400m that system falls to pieces, and everyone wants to shoot antelope at 1000m now. I see this as a fast way for guys that don't spend 2 hours a day working their dope and spinning turrets but want to get a fast accurate solution past say 400m, but are not ready to go to 1000+. The other option I like is you can get a true BDC reticle for your setup, in that you can set the scope to illuminate multiple dots at once corresponding to yardage. I'm not really a BDC reticle guy, but usually because they are never accurate.
If you are not buying it to use with the BDX system, I'd go another way. I'd also say if you are wanting to shoot targets, I'd go another way, you then have the time to dial and the distance of those clicks is tighter than the SIG scope can illuminate, so you get more precise aim points.