What does 1&1 do well? 1&1 Internet is a respected company and they offer reasonably-priced services. You can easily manage domains on the 1&1 control panel, and point unused domains to your main website.
What does 1&1 not do well? The online email reader and editor could be a lot better. Sometimes the customer service takes a bit of time.
What do you wish you had known about 1&1 before using? Support is available by phone and they are very helpful. WordPress service is great for customers that have little or no tech expertise in-house.