Has anyone found a discreet/effective solution for determining who is at your front door?

It seems like many of the peepholes and electronic viewers on the market suffer from a variety of problems, such as: low quality/reliability, poor/fuzzy/foggy resolution, blind spots, aesthetic/size obstacles, installation difficulties, privacy/security concerns, usability issues, etc.

I would really like to find a device that was relatively easy to install, worked well under various weather conditions (such as bright sunlight, darkness, rain, etc.), was reliable, convenient, discreet, and secure.

Any suggestions?