Only issue I have is SECURITY. The developer should look at encrypting the cached messages.
Go to /User/Library/Application Support/Sparrow/ and navigate through your folders... the text files are plain text copies of all your emails that you can open in any text editor and fully read through.
I am a Free member 
Sparrow
Js80 reviewed on 10 Feb 2011
Go to /User/Library/Application Support/Sparrow/ and navigate through your folders... the text files are plain text copies of all your emails that you can open in any text editor and fully read through.
Very nice email client otherwise.
+2
Adobe Flash Player
http://kb2.adobe.com/cps/838/cpsid_83808.html#main_fixes_10_1_102