Thank you for letting us know, this is amazing. Checked the site out and you are right, they are indeed offering for a limited time only some free .info domains. Where in the world did you find this site!
1and1 is a reputed site. I have about 25 domains registered with them. It is perfectly alright to trust them. If you heard of Sedo, you'll notice that Sedo refers customers to 1and1 for domain registrations.