Considering the PS3 was a jump from SD to HD, online play was included out of the box, and the PS3 actually had exclusive games and next gen exclusive games within its first year, the PS4 isn't doing so bad in comparison.

Currently, PS4 is trailling 1.3 million behind the PS3 if you compare how many months each has been out, and that's not including the full month of May for the PS4, even though that'd hardly make a difference.  That's really not that bad when you consider the PS3 from the PS2 was going from SD to HD, it included online compatibility out of the box, and unlike the PS4, it actually had several exclusives and next gen exclusives within the first few months of release.  Almost no titles on the PS3 were cross gen.  

I know we'll see atleast 37 more threads from Nintendo fans about the PS4 not selling in Japan or doing worse than the Wii U, because they need something to gloat over when the Wii U outsold within five months of the PS4s release, and inevitably when the Xbox One surpasses Wii U sales.  I guess no one wants to give it time when they can praise it right now as a win for their preferred console and won't be able to when that time comes.