Pros

Contain a lot of information

Can help you organize your "flow"

Very apparent if your topic is too narrow

Help you choose your key ideas

Pretty easy to cite

You usually don't have to evaluate the quality of the information

Cons

May not contain exactly what you're looking for

You can get stuck finding all your information from one source

Information on topics can evolve quickly can be outdated quickly

One book per person

You may not have access to the information when you need it.

Pros

Information is very up-to-date

Databases contain information that has been professionally reviewed - it doesn't need evaluated.

Help you fill in missing elaboration and evidence

Databases are very easy to cite

Information at your fingertips

Everyone can access the same information at the same time

Cons

Your results may be overwhelming

You absolutely need to evaluate the quality of information available on the websites you want to use. Anyone can post anything.

Teachers have websites they will not allow for research, like Wikipedia

Internet sources can be tricky to cite correctly. It's also easy to forget to cite all the sources you use - you can get sucked into an information hole.

Databases require passwords

The internet may be unavailable