Although it's obviously MS Paint, it is well done. Littlepip's nose seems a bit too... pointy, and the 'gore and grime' has too much grime, too little gore. This could've resulted from the blood drying, but it should be more of a dark red than a brown. Of course that's not to say she shouldn't have any dirt on her, but a bit of both would look best.
The fourth and fifth panels (with the shotgun) were really well done. The magic around the trigger was a nice touch! Both of those panels were cool because they look like a FPS game like Fallout! Maybe you should consider adding some fallout related things in the first person shots though, (health bar, Eyes-Forward Sparkle, etc) but that's up to you as it would probably be a bit hard.
The window doesn't look so much bad as it does... awkward. Both the panels with the window have fairly similar shattered glass, which is a good touch, but the window is shaped differently both times. It feels a bit strange, but hey, it's just a minor thing.
The light coming through the window from the cloud cover seemed a bit bright, and it barely looked like there were clouds outside at all, but I really liked the shadow coming from the window bars, it was a nice touch.
Last little thing, Littlepip's mouth is disproportionate to her snout in the last panel. That sounds like a stupid gripe, I know, but it looks like her mouth is on the side of her snout.
I really dug deep to find things to say bad about this because the comic is coming along quite well! Sorry if any criticisms came off a tad harsh or stupidly anal, just trying to help make this the best gosh-darn comic it can be.