For many countries one of the waited new features on the iPad 2 is the support for 900 Mhz 3G. Typically a country has 2100 Mhz 3G in the cities (supported by iPad 1) but use 900 Mhz 3G in the countryside.

Just did 4-5 Mbit/s on the iPad 2 this summer in the finnish archipelago :-)

Apart from the extra memory and better cpu, the advantages of the iPad 2 really depend on the usage. I think with more memory the apps have got a bit more stable, the speed difference is not such a big deal IMHO. I don't feel the difference in weight and size. So-so upgrade in my case but the 900 Mhz 3G was worth it as our country has it almost everywhere.