Optimus Prime is a leader in the best sense of the word, taking point on every mission and never sending his team into any situation he wouldn't go himself. Dedicated to the protection of all life and the preservation of freedom for all sentient beings, he serves as a role model for his fellow Autobots.
Cybertron Prime in robot mode might just be the best Prime to come out in a long, long time. The level of detailing is awesome, as is the number of homages to past versions of the Autobot leader. His head features a removable mouth guard, reminiscent of Optimus Primal in Beast Wars (the TV character, not the toy). The front of his chest reminds me of both RID Prime and the Japanese Star Convoy. His arms look like those of Armada Prime and the complete package is a sight to behold. His posability is excellent and he has the almost mandatory chest cavity containing a removable Matrix of Leadership. There is really very little to complain about here.
Optimus' robot mode can be enhanced by combining with his trailer, which forms a kind of backpack for him. His legs get a little longer and thicker, too, and he gains wings. The result is a heavily armed, flying powerhouse with still excellent posability and a very cool look. Both cannons can be enhanced by putting in his cyber key, the left one opening up into a larger cannon, the right one deploying missile launchers. Bottom line, Optimus Prime is one of the best robots ever.
Sadly Optimus' vehicle mode isn't half as good as his robot mode. Transforming into a cab that, once again, is very reminiscent of the Japanese Star Convoy, Optimus combines with his trailer into what is supposed to be a fire truck. It does look a little like one, but there is no mistaking the cannons on top, making it look more military. Personally I don't particularly like this mode, as it tries to be too many things at once and succeeds at none. It does have a fun gimmick, though, being able to transform into a kind-of flight mode by flipping out the wings. The result looks a bit funny, but it does add spice to an otherwise unsatisfactory vehicle mode.
Like just about every Optimus Prime since RID, Optimus can combine with some other Autobots into new forms. In Cybertron these Autobots are Leobreaker/Ligerjack and Wing Sabre/Sonic Bomber. Leobreaker becomes a new arm for Optimus (his real one folding away), Wing Sabre becomes a substitute for his weapons backpack. Check out the Ligerjack combination in Ligerjack's review
and the one with Sonic Bomber
in his own review.
Possibly the most ecxellent Optimus Prime in a long, long time, at least when it comes to the robot mode. Sadly the toy is somewhat dragged down by a vehicle mode that is, at best, average. Still, Optimus is a great toy and I recommend it to just about everyone, except maybe those who are more into vehicle modes than robot modes.
Update June 4, 2008
: I've recently acquired a second Optimus Prime on the flea market, so I decided to take some comparison pictures showcasing Prime's various modes. Here we go: