Sony did invest insufficent into software side of things in the past, playing catching up for large part of last gen. But I think in the past few years to current, they have beefed up significantly in sofware side of things, & the results show. They are not far behind, or even on par with MS. There PS4 development tools have been praise by developers, the UI are generally well recieved.
The advantages MS had in the past in software side of things will not be significent this gen. Yes Sony do not have million of developers as MS, but not all of these developers are working on XBOX, & Sony only need to hire in hundreds, or maybe low thousand, but the best people for software work on PS4.
I am speaking as a developer (not software though, but principle is same) myself, in a big corporation.