Stuart,
Unfortunately, we somehow missed removing a style from the view, so we'll likely put out another point release to fix that, but below is an image of what it looks like with that fixed. It's a simple matter of editing /components/com_jlinked/views/loginregister/tmpl/default.php, searching for "45" and removing that whole style of "width: 45%; float:left". When done, with the JomSocial profile plugin enabled, the register form will look something like:
Even with the style left in, it will look better than before, but a little squished onto the left hand side of the screen. Again, all of the styles are overrideable through a new CSS file, so if you have issues with a certain field, you can easily add specific styles to clean it up now.
Finally, that picture is of the 'vertical' mode. The "Register Only" mode removes the login area from the top altogether. The register portion will look the same.
Would definitely like your feedback. We haven't looked at the Login / Register page in, admittedly, too long of time. Hopefully this is a move in the right direction!
Thanks,
Alex