I bought SD tool exactly one year ago, while it was a very fresh and young product.
For some reason, I trusted SD's name and proceeded to the purchase.
Overall, after one year of dealing with it i have made these conclusions:
1. If the media you are trying to recover is already in their database, it can work with only a few clicks. For me, this was the truth for no more than 10% of the cases i had. By the way, they have adopted a "pointing system", with which you earn a point if you score an uploaded algorithm as succesful. You lose one point for every un-scored download you make. Judging by the fact that the library is pretty messed up (you have to make various tries to find out which id is the one similar to yours), this gets a bit frustrating.
2. If the media is NOT in the library, then you can ask for SD tech support to connect to your machine via TV and have a look. This is usually the case here; they connect to your machine within a few hours usually, but i have to say that I also had a couple of cases to which the SD staff failed -or forgot or were too busy- to connect to my machine for days. I had to send requests every morning hoping for someone to get back to me. And counting the time-difference fact, i had to wake up at 3 o clock in the morning (local time) and send support request (or go to the office straight from the pub, send the request and then get back to what I was doing

). 50% of the times the support staff connected to my machine, they succesfully recovered the chips. The other 50%, well... read the following.
3. In case you are able to fill the necessary bits yourself (determine ID etc) then you are in luck.
4. (and most important) About 20-25% of the cases have FAILED using this tool, either because the tool wasn't able to identify chip, or it couldn't succesfully read dump, or whatever. From these cases, 80% were succesfully recovered using my partners' Soft Center.
Having said that, if i was to buy a tool today, i'd go for Soft Center or ACE. I don't know about ACE tool, but my partner who uses SC's, is very happy with it.