I think this is a real blow to the Russians. While 5 km after 3 months might not sound good, its 5 km through what has to be the largest and most complex fortification line in Europe since WW2. We are talking about defense in debth with miles of minefields, tank traps, trenches and with significant reserves.

If Ukranians keep pushing eventualy they will breach through... and then its rush to the sea.