A huge leap over older gen consoles cannot be said. Both uses different architecture, and can not be compared based on their increasing order of values. PS4 being more close to PC, we can compare the specs directly with PC, unlike what we could not do for PS3.
Also, the memory can not be compared with even the modern day PCs, as none of the PCs use GDDR5 memory as System RAM.
GDDR5 Memory running at 1500 MHz, can transfer data at 48 GB/s [value based on high-end video card].
On the otherhand, a DDR3-3000 [the best specification] at 375 MHz can provide a maximum of 24 GB/s.
But again, as the 8 GB is shared between the GPU and the System, nothing can be said conclusively.
As for games looking awesome, they always do when seen in trailer videos.
Rick