Some interesting facts:
Putin's approval rating is 86% according to Levada, an international company with offices all over Europe, 83% according to Gallup, one of the largest US based polling companies, and Pew Research (American based as well) has a similar rating at 83%. Several Western-based smaller companies have similar numbers, showing Putin as being tremendously popular.
Some facts about Russia over the 15 years, since Putin came to power:
Russia's GDP in the last 15 years: 938% increase
Russia's unemployment rate in the last 15 years: From 14% down to around 5%
Russia's inflation rate in the last 15 years: 7 Times lower
Russia's productivity in the last 15 years: 121% increase
Russia's average monthly wages in the last 15 years: Literally 15x higher
Russian central bank balance sheet in the last 15 years: From negative to 1,195 billion
Russian debt as a % of GDP in the last 15 years: From over 100% to 8% debt
Russia's happiness index hits 25 year high: Fully 78 percent of Russians say they’re the most content they’ve been in 25 years
Polls by Ukrainian research agencies find that one year later, Crimeans continue to prefer Russia: "Eighty-two percent of those polled said they fully supported Crimea's inclusion in Russia, and another 11 percent expressed partial support. Only 4 percent spoke out against it."
Major US research firm Pew Polls : "The latest survey in Ukraine by the Pew Research Center, reveals 91% of Crimeans believe the recent referendum was free and fair and only 4% believe Ukraine is correct in not recognising the referendum results. "
It's not hard to see why Putin is so popular in Russia. And its not hard to see why Putin is so popular among Crimeans specifically.