Mine arrived yesterday, did a photoshoot today when I saw no one else had yet, although I have since been beaten to the punch for photos, so I went and did a pictorial/text review. I will crosspost to the review forum as well afterwards. Splitting it into two parts because of the 10 file limit. Post 1 is robot mode and leg transformation, 2 will be alt mode and blast effect.
Throughout the review I will be calling him X-guy, because "Ultimate X-panse" is just bad, but I haven't though of anything I like better.
First up is a size comparison with his 'pretool' ss jetfire, and ss86 grimlock. He is taller than both, but only because of jetfire's hunched posture.
X-guy's biggest strength is definitely his robot mode articulation. His arms have 360 wrist swivel, 90 elbow bend, 360 bicep swivel, ~95 in/out shoulder pivot, 360 shoulder rotation, and a ball joint used for transformation that gives ~5 front/back butterfly and 90 upwards stretch. This last one especially allows him to do the hardest letter of YMCA for action figures.
His legs have '360' ratcheting hip rotation with ~95 of front/back clearance between back kibble and belt, his thighs have '180' of in/out pivot on a ratchet joint, but only 100 of clearance before hitting belt. 360 thigh swivel, double jointed knees, both ratcheted, with a collective 90 of front back due to leg shape/knee kibble, 5 past neutral in either direction ankle rocker, with an extra ~2 from the thruster being on an extra ball joint for altmode posing. Transformation joint lets him tap his toe impatiently. No photos here due to how straight forward it is.
Neck has full 360* so long as head's up/down hinge is all the way down or visor is over eyes, otherwise visor antenna lock onto kibble behind the head, locking into place. Up/down has ~10 clearance, eking out an extra ~2 with visor down. Visor rests at slightly below neutral when deployed, allowing him to 'look' down.
This brings us to the torso. Waist has 30 clearance either way before leg hits back kibble. Ab crunch(!) has 10 forward clearance before chestplate hits belt, and left/right spine rocker pin(!) has ~2 clearance at best either direction, but this goes up to ~7-10 when ab crunched forward. It is also loose, at least on my copy, and flops some, although the lack of clearance in neutral posture keeps it from being too annoying. The really impressive thing about both these joints is that they are completely gratuitous; they aren't used in transformation, only for robot articulation. Here are pics showing them off, with the chestplate transformed out of the way.


Most of the figure's transformation complexity is from the leg transformation, with a really clever double turnaround on the leg panels. However, the firmness with which they tab in can make it difficult to untab them to transform in either direction. You will also probably need to sacrifice a small child to get the various ratchets lined up perfectly to get things to play nice the first few times you transform it.
A note for transforming back into robot mode: there is a tab in the inside of the tailfin inherited from jetfire. It is important for clearance reasons that it tabs into its slot, shown here.
As stated above, altmode and blast effects in post 2.