One of the best mecha games out there
After playing through the game a number of times in a row, I can confidently say this is my favorite mecha game to date, beating out Armored Core, Another Century's Episode, and Zone of the Enders.
While the game system itself isn't that spectacular, it's solid at least. It has everything you'd expect out of a good mecha game, meaning a variety of attacks, a dodge-boost function, and a wide variety of mecha. The system is good, it's just not as good as something like Zone of the Enders.
That being said, the game more than makes up for what it's lacking in system in presentation and characters. The game does a better job at making the player feel as if they're in the middle of intense giant-mecha battles better than any other console game out there. It feels good to be able to take on the Gundam using a Zaku II in Zeon's assault on Jaburo with enemy GMs being dropped in left and right and having cannons laying down fire against you as Gow assault carriers fly overhead. The game actually come across as fairly chaotic, despite actually giving the player entire manageable missions. A lot of the atmosphere actually comes from the background of the game, in which you'll see beam lasers, machine gun shots, rockets and explosions all around outside of the playing field. It may not seem like much in a written review, but it seriously adds a lot to the game. Atmosphere and mood matter in gaming.
Aside from the atmosphere of the game, the original characters in "Progress Mode", in which you customize a pilot, are actually quite interesting. Personally I would like to see some sort of other work, such as an anime or manga, detailing their story more in depth.
In short, Gundam Climax U.C. is a mecha game with a solid system, interesting characters, and spectacular presentation. If you like mecha games, or like Gundam, chances are you'll like this game.