The only bad thing Putin has done in this situation is not acting quickly enough to liberate the Donbass region from the new Ukrainian regime. The new government of Ukraine was funded and installed by the west, primarily to weaken Russia and force them out of their Crimean port as revenge for Russia's involvment in stopping the west from invading yet another sovereign country (Syria). Another reason, is of course, like always is natural resources. The black sea is extremely rich in resources and Eastern Ukraine is rich with natural gas and precious metals. This all stems from the Syrian conflict. The west wants to force Russia out of Crimea and Ukraine so they can weaken their navy - and place missiles on their border.
What many don't realize is that the only reason Crimea or Donbass (East Ukraine) were even part of Ukraine is because Communist leaders assigned them to Ukraine. They had historically been populated by Russians and were part of Russia in the Russia empire. Lenin added the east to Ukraine and Kruschev added Crimea to Russia. It is only fair to allow the residents of those two regions to choose their own fate.
A lot of people like to make the argument that the Russians living in the East and Crimea "don't belong" there. Why not? Because a couple of communist dictators assigned their homeland to another "country" ? When Albanians who lived in Kosovo, a historically Serbian region, wanted independence, the West went to war to "free" them. The situation is similar in Ukraine, except this time, it is in the west's interest to create a hostile government in Ukraine so that they can place military bases for the inevitable showdown with Russia that they have been planning for a long time.
Ukraine's army has deliberately targeted and killed civilians all over the Donbass region, simply for wanting to choose their own fate. Yet, the west doesn't report this. It doesn't fit the narrative. Apartment blocks and schools have been bombed. People have been killed in markets as Ukraine's government performs collective punishment for the actions of the rebels who fight for the freedom of their people. The east's rebels, unlike the Ukrainian government, do not target civilians - only military targets.
Putin's mistake - and crime - was not intervening with direct military action in Eastern Ukraine like he did in Crimea. That would've saved many, many, innocent lives. However, Putin, being corrupt as he is, is more concerned with his own money rather than people's lives. Ukraine needs to respect the will of the people, like the U.S always claims is right, and allow Donbass and Crimea to be independent. They can have Kiev and Lviv and run whichever government they want there. That's Ukraine. Donbass and Crimea were never Ukrainian.
I am ashamed that the government of my country is so instrumental in murdering civilians in Ukraine, but people are too ignorant to realize what's really going on. It doesn't matter if it's a republican or democrat in office, they follow the same foreign policy of aggression.