I mentioned this to DH, who commented that its a good commercial move because good young male employees were particularly difficult to keep hold of as they were much more likely to change jobs than women. He's changed jobs once or twice every couple of years for both career progression and circumstances beyond his control, but this would be one of the few things that would make him reconsider doing that even if he was offered more money elsewhere. It was something worth being loyal to a company for. Given the cost of recruiting him (and other staff if his replacements do similar), it does make more financial sense than it initially sounds.
From a woman's point of view, I think that offering better terms also makes good sense as good employees are more likely to go back to work, rather than give up or go part time if they are offered this. Equally there is something to be said for it if there partners work for virgin and they don't as if its shared leave, then they can back to work quicker (or if they are not entitled to as much) whilst their partner shares the leave which ultimately may make the transition back to work easier for all concerned.
I know that DH would have loved to have taken more leave (he still would - DS is still only 9 months). Economically he had to take half his paternity leave as holiday rather than paternity as he was only entitled to statutory after a week which wouldn't cover our bills.
I hope more places start seeing the value of the idea tbh. I don't think its just a gimmick or a PR stunt, but a good way of retaining high quality staff.