Yeah, this is a lot better than the other one. The segmented plates and joints make it look like it was designed to move, and not just look cool. Also, it kind of looks like it has a Federation deflector dish on its chest. I doubt that was intentional, but it's kind of awesome.
I like it better because it doesn't have a neon pink neck. That just messes with the color scheme. This makes me think of Mass Effect's husks a little bit, but it looks like a cyberpony and I think it looks awesome. RadagastNyrr has a point about the joints though.
Definitely a step in the right direction, and on the whole it's an interesting design with a nice aesthetic, but I'm noticing a few possible design flaws.
Take a look at the legs for a minute. Now let's look at the motions expected of a horse/pony.. (Alternatively, see here) Now, while I wouldn't really expect a cyberpony to be moving at the gallup seen in that image, I would expect them to have the requisite number of joints, and you're missing joints at the hoof-area, allowing for 'wrist' and 'foot' motion. This is particularly glaring in the rear legs, which comes off (to me at least) as rigid to the point of impeding mobility even at a walk.
Additionally, it might just be me, but I'm finding it really difficult to read depth into the pony's rump area, which I'm tempted to blame on three things: 1) The lack of highlight on the apparently intended 'rise' where the shadow drops off, 2) the sheer size of that cylinder running through it. Maybe it's just me, but the design might improve if you reduced its diameter (keeping the rump the same though) by...I dunno, a quarter maybe. 3) The pony itself seems to be at an angle, but the symetrical shading of the cylinder makes it seem to face us directly rather than at a matching angle. (Do note though, these are just my instincts as a viewer. Lacking practice drawing/shading myself, I could be completely off base)
Given the solid metal on the back, it seems very odd to me that the underbelly would be so completely exposed. I could understand it to a degree if the back was segmented to allow movement, but with it solid like that...I dunno. It feels like either the back needs to be less rigid to justify the belly, or the belly needs to be more rigid to justify the back :/
Again though, I'm liking the general aesthetic. It feels like a more advanced cyber than what has appeared in Doctor Who, and that fits with the changes in cybermen designs, making this feel like a natural progression.