I don't have any doubt that many aspects of Russia's invasion of Ukraine have been disappointing to Putin. Advances everywhere have been slower than they expected. But as
@punkin says, they have done much better in the south than the north, as shown on the map below.
I see two big threats to Ukraine in the near term. One is if Russia succeeds in taking or isolating Odessa. If that happens, Ukraine will be essentially landlocked -- no outlet to the Black Sea. Odessa is also Ukraine's 3rd largest city.
The second big threat is that the Russians succeed in surrounding Ukraine's major cities, which would make resupply a much more difficult challenge. I believe they already have Kharkiv (Ukraine's 2nd largest city) surrounded. No matter how brave the Ukrainians are, without food, medical supplies, and ammunition their situation could rapidly become hopeless.
The two sides are supposed to meet again tomorrow, but those talks have not been fruitful so far. Russia has agreed to provide safe evacuation corridors to reduce civilian casualties, but they haven't kept their word yet.
Here's today's BBC map showing Russian progress.
