I'm not going to pretend I'm an expert on the guy, but the fact he is lauded for the counter pressing style that we all begrudgingly admire from the clubs that seem light years ahead of us just now, and is so hghly regarded by Klopp and Tuchel, is enough really.
Personally I'm not expecting much between now and the end of the season, because even wth a top manager it'll be a long process, and Rangnick seems better suited behind the scenes, but if he can at least have got some way down the road at getting his philosophy accross to the players who are worth keeping, and identified the players that need moving on, then it's not 6 months wasted.
Unless I misunderstood Rangnick is having a big say on the next manager, so it's not like we'll be rippping it all up again in the summer, more the next guy picks up where he left it, with Rangnick then helping build the new team.