G.I Joe: Rise of Cobra is a extremely flawed, but decent movie, it engages audience purely as an entertainment medium, nothing more. It is successful because of that. In 2012, for the 3-D sequence, the movie is delayed to 2013 and for some reason, most of the characters has been replaced, makes the movie kinda in a limbo. Is it a sequel? Or a reboot?
The answer is kinda both. G.I Joe: Retaliation is somewhat more enjoyable if you watch it as a full reboot, but you can't ignore the predecessor's storyline, because it is connected. In the movie, only Duke, Storm Shadow, Snake Eyes, President of America, Cobra Commander and Zartan returned for the sequel, the rest of the casts are brand new. With Bruce Willis, The Rock and Adrianne Palicki join the ensemble cast.
Plus points of the movies are the cheekiness of Rise of Cobra is still there, some good one-liners, comedic moments from the casts are notable. The CGI and audio effects have been improved significantly from Rise of Cobra, with seamless visual effects and greater audio power. Bruce Willis looks great as General Joseph Colton, the original G.I. Joe. Despite the action being more grounded, more realistic than its predecessor, action sequences is still a treat!
Now the minus. What the hell are they thinking when they are making this sequel??!! They are calling this a sequel but replaced most of the cast, Joseph Gordon-Levitt is gone as Cobra Commander, Ripcord, Scarlett, General Hawk and etc is all gone! And not to mention Channing Tatum, actor who portrays Duke has little screentime and all of a sudden has a better friend in Roadblock (The Rock) and didn't mention his old 'bro'. Due to that, most of the time, it makes the story non-relevant anymore, even though it doesn't have a good story to start with.
In conclusion, G.I. Joe Retaliation is a great all-out action movie with great effects in full force. But, it must be treated as a reboot rather than a sequel in order for it to be enjoyable, which I did. If you are in for the true sequel of Rise of Cobra, you will be disappointed.