When you say "AK-47" I assume that you mean a semi-automatic clone of the AKM, which shoots a 7.62x39 round. These rounds will punch through multiple walls and car bodies, and are therefore not favored as a home defense round due to the excessive penetration and consequent danger to innocent bystanders. I would not pick up a 7.62x39 AK in self defense until well after the S had already HTF in a big way.
But there are other semi-auto AK variants tht you might consider for home defense. Arsenal of Bulgaria, the Polish Archer, and Zastava of the former Yugoslavia all make AK variants in the 5.56 Nato / .223 caliber that are currently being imported into the US. This round, especially in lighter weights such as 55 grain bullets, carries a lower risk of over-penetration. Both the Bulgarian and Yugo guns are available in a "pistol" configuration (essentially a short-barreled AK without its rifle stock) and the companies importing the Polish Archer are talking about bringing in a pistol configuration as well.
AK's also are available in shotgun form. The best of these imho is the VEPR 12. Unfortunately, both the VEPR and the Saiga shotguns are no longer importable due to recent sanctions against Russia. I have also heard of a Chinese copy of these Russian designs which I think is still being imported as the Catamount Fury in 12 gauge.
Both the 5.56 and shotgun configurations retain the AK's essential simplicity, which allowed it to be fielded and maintained effectively by illiterate peasants, initially in Russia, and across the globe ever since. So an AK variant could be a worthwhile consideration for a neophyte American as well.
But whether you choose an AK, a revolver, or some modern semi-auto pistol, it's still important to learn the firearm, the basic rules of firearm safety, and to target-practice as much as you can.
-app