The backlash is odd. The S3 was itself more an evolution of the S2. It's just that the market finally really noticed the galaxy line and it took off. The S3 was/is wildly popular... generally considered the best on available and really the first that the public saw as superior Apple's baby. Is it a surprise that Samsung decided to just update it rather that do a ground up redesign?
They took the top phone on the market, updated its hardware, kept the same basic layout and made a few tweaks...nothing wrong with that. Ok, sure, that is what Apple has done with the iPhone from the get go....look how it turned out for them.
We hyped the S4. Samsung kept it quiet, but everyone keeps their new stuff under wraps... no matter of it's the top dog or just the basic value line. Samsung wants to sell a lot of phones...that is what that are SUPPOSED to do.. and they will sell a ton of S4s.