New releases have a habit of floundering in January, which tends to be one of Hollywood's biggest dumping grounds. Even this year's big January horror release, which is commonly a sure thing, floundered. What does tend to do well are the prestige pictures that opened late in the previous year (often in limited release) and finally expand in the new year, riding awards momentum to solid box office.
Two of these ('Lone Survivor,' 'Her') aren't technically opening this weekend, but they are expanding to many more theaters. That, along with the year's first Hercules flick (yup, there's another one coming in July) and the recent slew of high-quality holiday releases, make for a very crowded cineplex.