Start 2013 in Is. The Reykjavik Grapevine - Life, Travel and Entertainment in Iceland / 4G Coming To Iceland
Germany --available Now. Samsumg Galaxy IIIs works fine on it --haven't tested the download though.
Belgium - Belgacom (Proximus) available Now (They started rolling it out in JUNE 2011 --long time before UK). Belgacom extends 4G network in five more cities - Belgacom Group
No experience with the others.
UK is slightly slow out of the blocks on this one.
The Belgian service works brilliantly -- definitely a HUGE improvement over 3G and most "Public Wi-Fi" stuff --but watch your data usage limits since watching an HD movie on your smart phone will just eat away at your data limits. !!!
Germany it's fine too -- can't say I've tested the French and Dutch service. For the Is service I'll test it when its rolled out.