This information is from technet and below here is what I find of interest. All information below is what Microsoft recommends:
Document size limit
You cannot configure SharePoint Server 2013 Preview to store documents that are larger than 2 GB This is a built-in absolute value, and cannot be exceeded by design.
There are some limits that you can exceed the default values of, but as you increase the limit value, farm performance and the effective value of other limits may be affected so it is at your own risk.
Recommended guidelines for general stuff
These limits are set so high that the company I work with never have to be bothered at least…
300 content databases per Web application
250,00 site collections per Web application.
Microsoft strongly recommends limiting the number of site collections in a content database to 2,000. However, up to 5,000 site collections in a database are supported
10 application pools per Web server
Microsoft strongly recommend limiting the size of content databases to 200 GB, except when the circumstances in the following apply:
If you are using Remote BLOB Storage (RBS), the total volume of remote BLOB storage and metadata in the content database must not exceed this limit
Content databases of up to 4 TB are supported when the following requirements are met:
Disk sub-system performance of 0.25 IOPs per GB. 2 IIOPs per GB is recommended for optimal performance. You must have developed plans for high availability, disaster recovery, future capacity, and performance testing.
(We are not using SP backup, we manage backup using third party products.)
If you exceed the limit:
Upgrading of site collections within these content databases is likely to be very difficult and time consuming. It is strongly recommended that you scale out across multiple content databases, rather than exceed 4 TB of data in a single content database.
Content databases with no explicit size limit for use in document archive scenarios are supported when the following requirements are met:
You must meet all requirements from the “Content database size of up to 4 TB” limit earlier in this article, and you should ensure that you have carefully considered all the factors of that limit.
The sites must be based on Document Center or Records Center site templates. Less than 5% of the content in the content database is accessed each month on average, and less than 1% of content is modified or written each month on average. Do not use alerts, workflows, link fix-ups, or item level security on any SharePoint Server 2013 Preview objects in the content database
More limits… sure
Of course there are a lot of other limits and boundaries, but they are in such a large scale (as mentioned before) that I will never run into those limits anyway. If you are interested in those, find more on the technet link above.