It looks similar to Credit Karma (I haven't download the Score & Report app). Just as long as you keep in mind that's it's not an actual FICO score, and use it to look more at your report to keep an eye out for suspicious things, you should be fine.
Everybody and their brother are coming out with these free reports and sometimes scores, so we'll probably see more in the future.
Yes I've used Score and Report. I agree it is is useful to watch suspicious items and as a warning tool for inquiries, new accounts etc. I've also used Credit Sesame and the real Fico scores offered by most banks now. I have noticed that the free reports, that typically use transunion, are 10-20 points below my Fico scores. Not a big deal as these free score reports use different weights on number of cards/loans, outstandings, usage, etc. versus Fico.