There's nothing inherently wrong with DRS, but the application of it across the first two tests has been questionable at best. For a system that's supposed to remove howlers, there have been howlers given out when they shouldn't have been, and not outs given when they should. Can't really blame the technology, just the incredible ineptitude of those trying to fathom its proper usage.
Like video evidence in rugby union, or like hawkeye in the tennis, it's supposed to remove the controversy of wrong decisions, yet in these tests so far, the most controversial aspects of the game have been the legitimacy of certain decisions.
Of course that shouldn't mask the deficiencies of the Australian team, but then, I doubt it will.