After spending some hours with skimming documents about Synereo, the first question pop up in my mind is,
"It may resolve problems what Steem doesn't now, but will it resolve what Steem already solved?"
Here are my thoughts.
Where is the Fee part?
The biggest concern is a fee system. It never mentions about fees in the documents while Steem white paper clearly describes about the importance of the fee system. Yes, it is cleaver! You should not tell your weakness to your opponents. If my guess is correct, Synereo will have some fees for every activities while Steem provides zero fee system.
Sub-second Block Time and over 40k TPS
I am really dubious about these goals of Synereo. Are they really achievable? I cannot tell the goals can be or not, since everything is undetermined now. Meanwhile, Graphene engine, which is a basis of Steem, already proved its high throughput, over 100 TPS at least and can easily go up to 1k and possibly 100k in the future.
Hot Money Wins
While Steem gives a great advantage to Steem Power holders who locked in their funds at least two years, Synereo does not discriminate long-term investors and short-term speculators. This can attract a great amount of money in a short-run. But in a long-run, you can imagine the downside of the influx of hot money.
Reward with Volatility
Combined with the third point aforementioned, rewards in Synereo can be very fluctuating. This makes people to convert the rewards into more stable currencies, such as BTC, USD, or hopefully Steem Dollar. This will be the rule: Once you got rewards, you should dump.
Conclusion
Synereo is a good rival for Steemit and every competition is beneficial. I hope Synereo will improve its system better and better, and Steemit too.