Until this morning, new notifications highlighted the user's avatar, biography and simple service usage stats, like total tweets, as well as the following and follower metrics. Below this, updates displayed up to three users who they follow who follow you, as well as up to three users who you both follow. The top bar was the original Twitter blue, featuring only the corporate logo and mascot.
The Older Notification Emails (from earlier this morning)
Now, the same HTML e-mails are aligned to display in the center of the message, and the blue bar has been updated to have image from the world map behind the logo with a more muted tone in line with the new welcome page. Instead of the two practically similar folllower/following details, you get one line, showing how may users you follow who also follow your new follower. This connection actually turns the relationship on its head, as instead of caring if others follow you too, you find if your existing connections find this new person valuable - probably more useful.
The new Twitter notification emails.
In the first array of new notifications I've seen, only once has the follower shared more than 3 connections with me, but Twitter did display the number of connections (8) with three select avatars.
As before, the first action in the fine print is to report the user for abusive behavior or spam, and the second is to stop getting such notifications. If you have thus far avoided unsubscribing, the new updates are not just more pleasing to the eye, they might actually provide more signals to indicate to you if the stranger has value.