Funnily enough, I was toying with a similar design to that - sort of Firefly-esque, but smaller, and also with a more curved and organic body like the Stingray.
Sitters' other antimatter-powered aircraft, the Dragon and Starchaser, have both had more angular bodies than the Stingray. I think a rounded body for the Raptor would work very well and help it feel like it and the Stingray share development and represent the epitome of Phalanx' research into UFO technologies. I think that also calls for alien-material blue in the textures, as well as those depressions/extrusions and green glowies.\
I do have some additional irks with the design, in addition to what Winter says. (Of course, I hasten to add, he's the art lead and not me.
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Having the entire cargo area drop down has a number of disadvantages for a combat transport. Engineering-wise, it puts a considerable amount of complexity into the design. The hoisting mechanism, whether it be fluid or electrically powered, concentrates a lot of the stresses into a few vulnerable points. In addition to the extra fragility, it adds weight, and while extra mass is fatal for any spacecraft, it is ironically an even stronger concern for human-built antimatter powered spacecraft. Extra weight translates to an increase in fuel consumption, and antimatter is too valuable to waste needlessly.
There are a few combat-related reasons why an elevating platform is a poorer choice than simple doors or ramps. It takes longer to deploy and retract than a simple door. It physically moves the entire squad, potentially causing disorientation in the vital time of deployment to a hostile LZ. It also provides much less cover - the only cover is the two fins to the side, leaving the entire squad vulnerable to fire. Not only that, but it exposes the lower parts of their bodies first, and only when the entire soldier is exposed to fire does he get a chance to see the battlefield. He must also wait for the platform to be lowered far enough that he can jump out, because the craft can not fly with the cargo bay open lest the winds sweep across the entire crew, and the stresses of maneuvering will be focused on the hinges and supports.
Of course, that's nitpicking at this stage - the general shape and ideas of the ship I like very much. I'm just, well, nitpicky.
A lowering platform is a cool idea, but I don't think it's practical in the least for a combat transport. (Things become a different matter if it's more of a civilian or tactical transport - in that case, the loading advantages of a lowering platform outweigh the disadvantages I've given above.)
