The MS-15/H Gyan (Xavier Olivette's Custom) is a custom alternate Qwux (GQuuuuuuX) version of the classic Gyan, a 'knight' themed mobile suit, which has further been expanded on with a gigantic lance, whereas before it only relied on its rapier beam sabers and missile shield.
Aesthetics:
The kit seems to follow the same height scale as the old Gyan at 20 (19,9) meters tall or 14cm as a 1/144 model.
Xavier's Custom is a 'white knight' themed mobile suit with green-gold trim in a qwux style design with a tall collar, smaller head and wide hips, blending a more semi-realistic style with sphere fuel tanks (on the lance), fuel cables on the thighs leading to the rear thrusters and likely other considerations that I'm not seeing.
Personally, to me qwux designs looks less realistic and less believable, even if they're designed to look light weight and maneuverable - They're a little too creative for my taste, even if they lean into the old designs (like the same backpack from 1979 - arguable the Gyan's weakest design point).
The kit does not have color correction as such, instead it has a sticker sheet with 25 individual green-gold trim stickers, 1 symbol decal and 1 pink mono-eye sticker. Despite looking difficult, they're mostly easy to put on. The worst are the shield ones that have to bend around corners, which makes them prone to peeling.
You can simply opt not to use them, though I'd say they look pretty cool and unobtrusive.
Mechanics:
Articulation is 5/10, though it might have been built with consideration for the heavy equipment - Single elbow bends and barely any internal shoulder movement make for limited movement, but they're also stiff and capable of lifting up the lance and shield without sagging.
The legs have a better range, but the side skirts, rear thigh thrusters get in the way of each other. Old mobile suit designs might be blocky, but they're well considered - This one, not so much.
The mono-eye does turn and tilt, but it's so tiny inside the head that it's hard to manipulate. It's most impressive feature (besides being able to hold the lance) is a backwards 75 degree ab-crunch, but next to no forwards movement (again, probably due to the heavy equipment).
Equipment:
1 "Hakuji" Lance - The rear thrusters move a little but look like they shouldn't. It comes with a stand so the model doesn't tip over holding it.
1 Weapon Stand with extra alternate adapter pieces
1 Missile Shield - Sits on a gigantic arm brace and can pose quite well - There are 6 hatches that open to reveal missile launchers
2 Rapier Beam Saber Hilts - These sit on the thighs and they come with short and long handles, short for storage and long for holding them. The problem is that the short ones are so difficult to take out, that unless you never take them out, might as well put the long ones in
2 short yellow Beam Effect parts from 2005 - Perfectly adequate and fit the rapier style beam saber well, proportionally
2 holding hands - Nice details, but they suffer under the weight and often split open
Conclusion:
This kit lives and breathes on its intricate surface details. It doesn't have a ton, but it does have a lot of shape detail, breaking up the surface everywhere. I find the antenna makes it look like an RC toy, which is silly and the top of the head tends to fall off.
I find that a fun pose to put it in is to hold the lance upwards, making the whole thing 30cm tall.
Mechanically it's competent and dedicated to what it does (carry a huge lance) while also letting you throw it into some poses.
It's a 'hit and miss' sort of kit for me since I like some of the appearance, but not all of it and it doesn't do much else than being immobilized by its own big weapons, depending mostly on its stand.