YouTube keeps showing the Google+ integration box and you can temporarily bypass it by reloading page. You can also go to youtube.com/account and click "Link channel with Google" to see the box.
This page shows more information about your options. "Profiles are subject to the Google+ Names Policy. The name on your profile should be the one you're commonly known by. Pages don't have name constraints, as names vary greatly among brands, business and organizations."
You have 14 days to change your mind. Just click "Temporarily disconnect Google+ page/profile, and use your YouTube username" in the account settings page.
What are the changes? Your channel will use the name and photos from your Google+ profile/page, it will link to the profile/page and you'll also see Google+ notifications and links in the YouTube navigation bar.
You can also create multiple channels. Use this page or click "switch account" in the navigation bar to switch to a different channel or create a new one. Each new YouTube channel comes with a Google+ page.