Downtown Disney is changing fast through 2018 and now the largest retail store in the Disneyland Resort, World of Disney, will become part of that change. Little has changed in the store since it first opened in 2000 but this reimagining will impact guests throughout most of the year. Be aware of what's happening so you won't be surprised when you visit.
One thing to remember is that very little merchandise found in World of Disney is unavailable elsewhere in the resort. The reason World of Disney is so popular (and was voted the Best Retail Location in Downtown Disney and the Hotels of the Disneyland Resort) is because it's a central location that features most items found in other spots around Disneyland. If the store feels too crowded during construction then I would recommend that you search for souvenirs in the parks.
Along with this refurbishment, the new virtual reality experience at The VOID has just recently opened, Splitsville Luxury Lanes is due to open shortly, and several new restaurants are scheduled to arrive later this year. Keep your eyes open around Downtown Disney in the coming months as it transforms into a new destination.