I did it on my last sim. You're in for a shock if you don't have a long enough runway! As stated above, you won't have reversers; if on a later MSN you will have auto regulation of the brake pressure, if not, easy on the brakes! Takes a damn long time to stop and mind you, we did it on a 3800m long runway (although at 8300 ft high).
As pointed also by others, it's quite a shocker (since you normally don't brief for that one, so you don't know what signs to look for). Everything just goes dark, you lose all screens and it even goes a bit quiet (after the gens cut off-line!). A reject will be what most would do, out of pure startle I think. Might not work on a short runway + high speed...
Would this one fit under "unambiguous indications that the aircraft will not fly safely"? As vilas pointed out, the go decision would be made under the assumption that everything will work fine after the longest seconds in aviation history. It should fly safely, but...