+ Unlike Bitcoin and other mining coins, all NEM would be distributed at the genesis block. NEM stakeholders are its own network nodes which verify the transactions and protect the network following a hybrid of Proof of Stake/ Proof of Importance forging mechanism. This type of distribution eliminates the need to have a mining industry which is an external force that imposes a huge cost to Bitcoin and other POW networks. The computational arm-race is avoided by using the hybrid of Proof of Stake/ Proof of Importance forging mechanism.
+ A novel method Proof of Importance forging that rewards the nodes that re most important to the network, not the nodes with the biggest number of NEM.
+ Support for colored coin implementation and the asset exchange is designed in the beginning with advanced features such as automatic settlement, assets listed with an expiration date. NEM focuses on the usability of the asset exchange to make them the premier platform for fundraising, asset listing, token issuing etc.
+ Secure messages for contract storage.
I am big fan of decentralization, and I am not sure if this kind of coin would represent level of decentralization other meta-currency's represent. Actually this "arm-race" as you describe it kinda make sure we wont have any dominant power that could put any kind of influence on people money. Here old user would have large advantage over new users. Of course additional cost created while mining is a problem but shouldn't we upgrade it, make compute power more useful insted of removing it...
That is the key question around POS vs POW. Personally, I think there are only a few thousand BTC miners that have invested enough in hardware to mine competitively. So, I don't think NEM will be drastically more concentrated than BTC. But, NEM's success will depend on people actually using it as a currency and not hoarding it. We'll have to wait and see how good a job the community does with that.