Vlad is the lead developer for Casper which is the proof-of-stake protocol meant to solve Ethereum's scalability issue.
He further explained himself in a subsequent blog post he made yesterday. Full post here.
"I didn’t make that tweet because Ethereum isn’t safe or scalable, really, I did it because I find the current level of euphoria quite offensive. Maybe it isn’t my place to keep euphoria in check. Maybe it is. I don’t know. But I will probably continue to express myself by turning my feelings into radical, unnuanced tweets nonetheless."
"Finally…"
"Is Ethereum safe? I don’t think so. I absolutely cannot guarantee that the network won’t be 51% attacked (though I would like to believe that a hard fork would minimize damage from such an attack). I cannot usually guarantee that a smart contract will behave as expected (I don’t need to mention that I sometimes like hard forks here, too, do I?). But lots of really smart people in the community are working hard towards making Ethereum safe, with smart contract formal verification efforts and with proof-of-stake consensus protocol research. I think that we will continue to make steady and impressive progress on these safety problems."
Though I wish the Ethereum team the best of luck I would have been somewhat displeased by such a tweet and blog if I owned some Ethereum.
This isn’t the first time the Ethereum team's public relation felt sketchy to some.
Dan Larimer asking Vitalik tough questions about Ethereum scalability issue.(2014)
Steem current super abilities of more than 10,000 transactions per seconds (theorically 180,000+) are pretty cool compare to 25 transactions per seconds for Ethereum without mentioning Dan's new development which might push Steem transactions limits to 100 million per seconds.
If you ask me, I much prefer the Steem Team for obvious reasons!
Nonetheless I would love to take this opportunity to send a sincere invitation the Ethereum core dev team to join Steem and transfer their blog here on Steemit.
After all, @rogerkver's post about Bitcoin scalability issues 2 days ago reached the top of the list and pocketed him close to 200$.