I don't think the lack of flash is a huge deal. QSPI flash will give very similar performance to internal flash with wait states. And you have a very cheap way to expand your flash size, if needed.
I recently did a brief survey of available QSPI flash devices and their characteristics, also looking at the emerging 8-bit-wide standards like HyperFlash etc. What stood out to me the most were the power-consumption numbers. My recollection from STM32 datasheets where they compare active power with/without flash was that the difference was fairly modest... 10-20%? whereas most of these external flash devices seem to eat quite a bit more, closer to being on par with the entire MCU active power. Is this mostly due to the increased capacitance of the external bus versus an internal bus? In any case, it seems like a significant disadvantage for external flash, power-wise. Maybe no one else sees these fast M7 parts as suited to low-power applications, but I do, as they use less juice than the application-processor alternative for similar compute performance.
I still think more SRAM is called for. Even neglecting the internal/external-flash power-consumption differences, just the fact that we are now at 600 MHz means that the flash-vs-SRAM performance gap is growing, and ST already has a competing chip with twice as much SRAM as RT1050. It looks like NXP intends to fill out this new family, so perhaps the chips coming next year will include some with 1+ Mbits.
Having now skimmed the reference manual a bit more carefully, I must say I am more impressed with the peripheral set than I was before. Does anyone know what is expected in terms of vendor libraries? Do NXP/Freescale's peripheral libraries tend to be any good? or at least better than ST's?
I would still like to see some kind of DSP acceleration peripheral, akin to ST's DFSDM. Or, if NXP really wants to blow us away, they could provide an optimized software DSP library to replace or re-implement the CMSIS-DSP API. As other members of this forum have demonstrated, CMSIS-DSP is not very well optimized, and substantial performance gains (2x or better) are possible, but with no off-the-shelf library this is a difficult, time-consuming process.