Maintaining the brakes goes - preferably - a bit further than simply changing the brake pads. The brake pads are only the last link in a process that starts with the brake lever and during the change, it is possible that air gets into the brake line.
Air can be compressed, while brake fluid cannot. This is what causes a spongy feeling at the brake lever. Brake performance becomes erratic and can decrease significantly when gas has gotten into the brake lines. So, bleed the brake lines after changing the pads, for your own safety.
Don't forget to top up the reservoir with brake fluid and always test your brakes in a safe place before you take the bike back on public roads.