Have a look round these forums, Aero, and see how many p*ssed-off aircrew there are around the place. BA, Emirates, Cathay, Qantas - you'll find examples of dissatisfied pilots in all of them, even though fom the outside things look great.
The thing is, most of the pilots who post about their Ts&Cs are either totally fed up with, or totally enthusiastic about, their airline. The lack of posts from Virgin pilots suggests that the vast majority are very happy with their lot. After a 24% pay rise for a 750-hour roster, that's not very surprising, though most are probably not aware of how well off they now are compared to other airlines.
Every airline has issues with its workforce, and Virgin is no exception. Rapid expansion causes strains that are sometimes difficult to deal with. Unions will flag up problems (hopefully) before they become serious, so that the pilots are aware of situations where the company's interests conflict (at least temporarily) with the pilots. That has recently happened within Virgin.
Virgin's pilots are on a fairly good deal. It's not the best in the European industry, and there are some issues that need dealing with, but most people are reasonably happy.