Their published privacy policy states:
- Your Evernote password is protected by encryption and only you have access to it;
- Your personal information and data stored in our systems is protected by various physical, electronic and procedural safeguards. It is housed in a secure facility and Evernote restricts physical and network access to this facility to select trained staff and regularly evaluates its technologies, facilities, procedures and potential risks to maintain the security and privacy of our users' data. As a rule, Evernote employees do not monitor or view your personal information or content stored in the Evernote service, but it may be viewed if we learn that our Terms of Service may have been violated and confirmation is required, or we otherwise determine that we have an obligation to review it; and
- Certain Evernote services support the use of standard SSL encryption to protect data transmissions. However, this is not a guarantee that such data transmissions cannot be accessed, altered or deleted due to firewall or other security software failures.
http://www.evernote.com/about/privacy/
The worrying thing is that they never state that the data is encrypted in storage to your password only. It is also quite funny that they think SSL is not secure, unless they are using a v2 or older I would place a lot of faith in SSL not being broken.
Back on topic, compare this to Dropbox
All files stored on Dropbox servers are encrypted (AES-256) and are inaccessible without your account password
https://www.dropbox.com/help/27
Evernote however does provide the ability to manually encrypt specific information to your passphrase: http://blog.evernote.com/2008/04/15/evernote-privacy-and-security/
Personally I prefer the Dropbox approach where I don't have to think about it. The data is as secure as the strength of your password.
In addition with Dropbox you can also run a Truecrypt volume for an added layer of encryption.
If you want the features of notes like Evernote with Dropbox on your iPhone try an APP called Elements. If anyone knows of an APP that can do voice recordings and turn them to text as well as photos and video and put them on Dropbox let me know.
EDIT 2011/06/21:
With the Dropbox revelations that actually they have your key and their staff and anyone else e.g. government can get access to your data Dropbox is actually a terrible model to compare Evernote against.
Also this recent vulnerability where anyone could access a Dropbox account for 4 hours without a password makes it even worse. Ignore everything I have said above about Dropbox: http://blog.dropbox.com/?p=821
HN discussion: http://news.ycombinator.com/item?id=2676630