Almost everyone who uses Gmail, or any kind of email service for that matter, sends and receives attachments on a daily basis. Apart from conveniently sharing files using Google Drive, email attachments are still very much prevalent in the Gmail ecosystem.
Keeping this in mind, the good people at Google have decided that all of us Gmail users can now receive attachments upto 50MB, up from the 25MB limit imposed earlier. However, the sending size limit will remain the same at 25MB, and Google recommends that users who wish to share files larger than 25MB, should use Google Drive. Google Drive allows users to share files upto 5TB in size, given that the user's drive account has ample storage.
Google says that the complete rollout of the increased incoming file sizes feature will be finished in 1-3 days for all Gmail users.