The only problem in 25MB attachment size limit is that not all email providers support such a large attachment size.
Other popular email services such as Yahoo! Mail and Windows Live Hotmail are only allowing 10MB for attachment size Good news is that now most popular email service providers do support similar limit on attachment size too, such as Yahoo! Mail and Outlook.com (previously Windows Live Hotmail), and most enterprise hosted email solutions such as Google Apps and Office 365, do allow 25 MB file attachment limit or even more. Anyway, your email with larger than 10MB attachments may still be bounced back due to over limit error. However, you can safely emailing big attachments between Gmail users, where number of it keeps growing everyday anyway.
Update 2: Send large file attachment of up to 10GB in Gmail
Update 1: Maximum attachment size limit for Gmail is now 25MB.