1&1 is great, we can do anything in the control panel.
The site is a bit slow. That's the worst thing.
Tucows is the best registrar in terms of update instantly, but their price is quite expensive.

For .uk domain names 1and1 are very poor - If you register a domain with them they can take 24 hours before they even bother to register it. I had one client that lost out on a name luckily I was in his office and he saw me register it, it was purchased 6 hours later by another host.

The other problem with them is the whois information is not real time - If I register a domain with most companies such as 123reg seconds later I can do a whois lookup on nominet.org.uk or even other registras such as uk2.net and it will be shown as taken - with 1and1 it wont show as taken for days? I don't understand how that works at all but try it - they automate the taking of your money but can't automate the registration of even checking of a domain.

The only reason I have every used them is they have given me 10 free domain with the hosting - I havn't used 6 of them as I prefer to buy elsewhere.