Video game retailer GameStop saw strong digital and mobile growth over the holiday period, but it wasn't enough to counter the notable decline in retail sales.

New game hardware sales decreased by 2.7 percent year-over-year, despite the launch of the Nintendo Wii U in November. GameStop says that it sold 320,000 Wii U units, describing the launch as "successful" -- although analyst firm Baird Equity wasn't so kind, instead labelling the figures as a "somewhat soft sell-through."

GameStop's real problem was its decline in pre-owned game sales. New software sales were down 5 percent year-over-year, which wasn't a huge surprise -- but in comparison, used product sales were down 16 percent.

GameStop says this was due to limited inventory and less promotional activity over the Christmas period, but Sebastian warns that there is "ongoing downward pressure on used software pricing and volume" due to the fact that we're currently in the very late stages of this console cycle.

However, there's no denying that GameStop is making progress as far as digital revenue is concerned. The company reported a 40 percent increase in digital sales, while its mobile business generated nearly $77 million in revenue over the holiday period.