One huge problem with all CPU coins and that is bots. What about viruses, etc. infecting computers and having them serve as miners for DRK, MRO and other CPU coins?
Not 100% bad as it does strengthen the network but it can lead to problems later on. I could hear the department of homeland security now. But then again, any
anonymising technology (e.g. darkwallet), will probably cause similar reactions.
IAS
I think cryptonote is great personally. No interest in DRK.
Many cpu- coin holder (mro for example) will claim that there is no such botnet on the network; (even with stats before any public pool existing looking more than a little skewed ) They will say it's mostly individuals, peppered with a couple of sysadmins who have few hundred CPU at their disposal; and finally those who rent large qty of cloud instances. One thing they will say; 'no botherder wants to add 'alpha' level coin' or 'all botherder want to keep cpu without stressing for more profitable activitys like viagra spam .'
You had to laugh when you saw the first 'optimization' of MRO.
https://github.com/NoodleDoodleNoodleDoodleNoodleDoodleNoo/bitmonero/commit/3cc45e9324a402aee91e2f46861b2ca393d711aaYes this was discovered 14 days AFTER launch from independent source. And team is so confident about anti- TMTO with things like above 'slipping' through the net? how many spotted this earlier and made nice profit
It's matter of time for optimized implementations. When it is private, everyone will say not possible .. we're all on equal footing! then when it becomes public an adjustment period- some will dump, there will be some drama , and then sentiment usually shift to saying 'it's good for the network'. That's assuming nobody is willing to hard-fork.

above: mandatory chart with squiggly line. (cpu-coin holder emotional reactions upon discovering cpu coin is no longer cpu only )
The same happen with Scrypt. many were GPU deniers, artforz, mtrlt and whoever else had advance knowledge & were laughing. then ASIC deniers while gridchip et al lining their pockets. I had an argument in december last year with a technically competent guy and senior member of litecoin community who was adamant 'it's not possible' to create a litecoin asic- what can i tell him when the damn unit mining away in front while he was so sure it can't exist. ?
Now people have turned around and seriously claim scrypt pow was
never designed to be GPU/FPGA/ASIC resistant
Allow me to introduce you Tenebrix, a cryptocurrency we
(mostly ArtForz, but I contributed the name, some minor tweaks and the logo, as well as windows portability suite and cool genesis motto
) have created to provide the community with a cryptocurrency with solid GPU resistance.
It implements a proof-of-work scheme based on scrypt, a cryptographic construct
specifically designed to resist creation of efficient GPU, FPGA and even ASIC implementations. You can find more about scrypt and how it can improve your stamina, masculine appeal and performance
hereTenebrix is intended not only to become the first and the best of CPU-specific cryptocurrencies, but remain so in the future (that's exactly where the Tenebrix Protection Fund will go...
That, usability/gui bounties, fixes and my dream of starting up a massive coin laundering "Historical Cryptocurrency Collector" Service 
)
It's a sort of sunk-cost fallacy anyone who invested into litecoin are exhibiting, considering the original premise is broken and it now offers no tangible benefit over bitcoin. but hey.. asics pushed the price of btc up so ltc will be a microcosm right guys? easiest profit ever,