Most 5.7×28 loads available in the US are loaded with varmint bullets designed for fragmentation. They work great on rabbit-sized rodents but lack penetration for defense against people. They can be effective under some circumstances, such as shooting fish in a barrel. Controlled expansion bullets, such as Ballistic Silvertips loaded by Elite Ammunition, provide better penetration of barriers without breaking apart. FMJ (Federal/Fiocchi) would be the next best choice, as would the original SS190 FN round but that one is hard to get. Then again, at this time it seems everyone is out of this ammo. One more argument for shopping in bulk early.
20-round standard and 30-round extended magazines combined with low recoil make this round a viable defensive option.
With a good holster, this fairly large but lightweight pistol can be carried comfortably.