What do you think?

Rather than defining him as bloodthirsty or somebody liking violence for the sake of it, I would say he simply didn't care about anything other than his ego; he was a cold as a fish individual (no offense to fishes). Michael's whole attitude towards other living beings could be defined by the phrase "I don't give a fuck", imo. Somebody could argue he did care about his father since he committed his first 2 murders to save him, but the fact he never stopped his life of crime later (even accepting to become the boss of the Corleone family), despite having more occasions to get out, proves there was something wrong with him from the beginning, in my opinion.

When I think "bloodthirsty" someone like Nicky Scarfo comes to mind.
For the most part,Mike had justifiable reasons to kill most of his victims.
Some exceptions that come to mind are the Lake Tahoe prostitute,and Roth.
The girl was a truly innocent victim,and Roth was finished.
I think that his killing as well as Fredo's were done both to satisfy Mike's ego,and to (in his mind) show the Mafia world that nobody messes with Don Michael and escapes vengeance.

I agree completely with Dwalin and Lou. Michael wasn't a psychopatic, sadistic killer like Scarfo or Anastasia (though he probably derived well-earned satisfaction from whacking Sol and Mac). But, unlike Vito, who negotiated first and used murder generally as a last resort, Michael's first choice was murder, almost every time out. And, no, he didn't give a shit about anyone. Early in GF, when Michael wants to visit Vito in the hospital, Sonny tells Clem to send a couple of guys with him. Clem says "Solozzo knows he's a civilian" (honor among thieves?). By the end of the movie, the collateral damage is piling up--the elevator operator and the other guy in the elevator with Stracchi, Barzini's driver, the hooker in bed with Tattaglia). Then there was that hooker in Fredo's brothel--killed just to set up Geary--Michael at his most reprehensible. Even when he seems to feel remorse, as when he makes Confession with Cardinal lamberto, he can't repent sincerely, because he can't let go of his ego and his need for self-justification ("I had my brother killed--he injured me.")

My two cents worth!

True Michael wasn't a bloodthirsty psychopatic, sadistic killer

I don't feel I have to wipe everyone out -- just my enemies -- that's all.
Don't know of his ego They hit him so -- He hit 'em back.

He stopped his life of crime after the Baptism massacre, carried out as per Vito's counselled strategy after his death and was living a "legitimate" life and public Benefactor until Roth started it

We recently debated in Was Michael a tragic figure? thread
True in the Mafia world it is a given nobody escapes vengeance Kill or be killed

I too reckon Mike had justifiable reasons even Fredo's --he injured me.") in view of this is the business they've chosen and they all know the consequences of what will happen as a result of their betrayal

Michael made the decision in the heat of the moment immediately after Fredo's Boathouse outburst but no doubt he could have been spared as we debated in various threads that he could have continued to keep him under watch same as until Mama died

Roth would always be a threat to Michael and wouldn't have rested until he was dead or destroyed
This is the man who didn't care if women and children were killed as long as Michael was

Geary set up hooker murder is no doubt deplorable and Tom's cold blooded handling of the whole situation was chilling and reprehensible too. It'll be as if she never existed. All that's left is our friendship.

I reckon, Vito the evil, ruthless, murderous original villain is seen through rose-colored glasses
Michael, like father like son and like Vito, negotiated first and used murder generally as a last resort, Michael's first choice was not murder. He's no different than his father

Khartoum and Hooker -- both were defenseless, truly innocent victims and I reckon, parallel could be drawn

The collateral damage is unfortunate, in the business they've chosen same as Don Ciccio's guards

Killing became a first resort for Mike by the end of the first Godfather. So I guess you can make a case either way.