Its actually amazingly useful.
I have had many systems that wont boot in any way, including safe mode. No amount of work in an external environment (windows pe, linux) would get the system back. Repair install was failing at random points. On those systems ReImage worked and got me a booting system back. It wasnt completely repaired, but it was close enough that I could finish the job.
It takes less time than most repair installs and does 10x the work.
I hate the nuke&pave method. If I dont have to I dont want to. ReImage saves a lot of systems that even most of us die-hards would end up nuking.