Yes. In the footer of the new catalog, you can follow the link labeled "classic catalog" to go to the old catalog at any time. For some library account services (e.g. establishing an account password if you didn't set one up when you received your card, deleting items from your borrowing history), you will still need to access the old catalog.
If your preference is to use the old catalog only, you might find it easier to bookmark or favorite its URL: