The Benefits of Lycanthropy (...)

You are immune to nonmagical and non silvered damage. Wounds made by such damage heal instantaneously.
You get advantage on all skill checks relying on smell and hearing.
Your Strength score automatically is increased to 18.
Fellow werewolves will acknowledge you with cautious friendship and don't outright attack, unless they know to feel threatened by you.
Whenever you transform into a werewolf, you regain half your total HP.
You know that there are 28 days to a moon, and you know what phase of the moon it is at all times.

The Negatives of Lycanthropy (most of them)

The DM may ask you to make a DC 19 CON save under specific circumstances. You may add +1 to your roll for every ally you can see within 30 feet of you.

Out of combat: Every night after sunset except the Full Moon. If you fail, you change form and lose control of your character. If you get below 19 but above 15, you may make WIS saving throws using the same pack advantages as you attempt to control your urges.
In combat: If your inner beast seems to be gaining the upper hand. On a fail, you transform into your were-form and attack the nearest living creature, even if that creature is a friend, until it's unconscious or dead.

While in your were-state (assuming you are at all aware), you must roll a WIS saving throw (you may add +1 to your roll for every ally you can see within 30 feet of you) each time you attempt to do anything other than:
- succumb to a blood-lust
- obey the orders of the Dark Master or the wolf who made you
When you transform, you drop everything you were carrying and your clothes may suffer.
Because you are running around all night, you can not benefit from a short or long rest unless it is taken during the day or you save on your CON throw. This is true regardless of whether you are aboveground or not.
- After three consecutive days without a long rest, take a level of exhaustion.
- You do not regain spell slots or other benefits requiring a rest if you transform during the night.