There are challenges, but the Republic of Congo is a lot safer than it's neighbour the Democratic Republic of Congo (DRC). Isn't it funny how countries with "democratic" in their name usually aren't?
I'm assuming you want to go and see the gorillas? Most of the operators are well aware of the safety risks and have made appropriate arrangements, such as pick ups from the airport, transfers and security at the lodges. If you plan to travel independently around Congo take care.... and be especially careful if traveling in the Pool region. The road between Brazzaville and Pointe Noire goes through the Pool region.
Speaking of Brazzaville - there's been a terrible incident there this week; a fire in an ammunition dump has caused a series of large explosions. There are 200 confirmed dead and it's feared scores more are buried under the rubble. The explosion has left 5000 people homeless. Latest reports say the fire which caused the explosions is under control (and possibly extinguished), but search and rescue operations can't begin because there are still shells exploding and large numbers of munitions lying around the area.
The Mpila district of the capital is badly affected (I've created a Google map here: http://bit.ly/J3wv).
Not sure when you're going, but if it's soon then avoid that district when in Brazzaville.
Phil at the safety hub almost 6 years ago