...Yes. Yes, he is.
The Spectre is literally the embodiment of God's wrath, God's vengeance upon the wicked. It's not entirely clear to me whether he is literally a angel.
His powers are for all intents and purposes unlimited. He could go toe-to-toe with the Anti-Monitor. There is a caveat, however: he only has powers and any kind of presence if he is bound to a mortal soul. Without, he is nothing more than a ghost. That was apparently God's safety valve.
But when he has his powers, he uses them to mete out vengeance on bad people in ironic ways. He turned the pre-Crisis Doctor Light into a candle and let him burn, for instance.
His original host was Jim Corrigan, a cop who got shot dead and was given the opportunity to become a supernatural avenger. Eventually, his soul went to his eternal rest, and the Spectre was without a host; then, he was co-opted by Asmodel, an evil angel, and used to punish all of Earth until Heaven intervened and a new host was chosen. That was Hal Jordan, who was in Purgatory after sacrificing himself at the end of 'Final Night'. He vowed to use the power to lead people to redemption rather than vengeance.
Eventually, Jordan and the Spectre were split apart again, and a new host had to be chosen - and that was Crispus Allen, a murdered police officer, with the twist that he was shot by a crooked cop with the name Jim Corrigan.
In the New 52, the Spectre is Jim Corrigan again.