I'm, using this plugin with WP 3.3.1 and it works great. But it fires a warning when you switch to debug mode in WP.
The function 'add_option_page' on line 49 of resize-at-aupload-plus.php, contains a deprecated argument: the user level.
Just substitute the third argument (8) with its corresponding capability 'administrator' and you are done!
So line 49 becomes:
add_options_page('Resize at Upload Plus','Resize at Upload Plus','administrator','resize-upload-plus','hz_uploadresize_options');
Hope to see this patched in a future release.
P.S.: Daniel, can you please specify the differences between the plus and the old version ('resize at upload') of this plugin? thanks!