Our studies against product listings and conversion rate/sessions show clear trends. Generally speaking, products that use the maximum number of features, images, title characters and description characters see higher conversion rates and sessions.
What does the data tell us?
Features
More features = higher conversion rates
Images
More features = higher conversion rates
Title
Longer titles = more sessions
Longer titles = higher conversion rates
Description
Longer descriptions = higher conversion rates
Always Test Before Making a Change
To help customers make a better informed buying decision, you should always test using the maximum number of features and images. On average, those to use the most number of features and images have higher conversion rates.
Having a longer title often means more keywords, which means more sessions and clicks to your product. This is why it is important to test for sessions while running a title test. On average longer titles and descriptions mean higher conversion rates.
These are of course averages and the results specific to your products may vary. You should always test any change to a product, so you know for sure the change is going to drive up your profits instead of hurting them.