Hello!
First of all, thank you for submitting your work to Critique-It! We're very glad to be of help.
Second, this work will be critiqued by =MimozaBlooming, and you're more than welcome to poke me about any edits and such you make to it, whether the result of my feedback or not; in other words, I'd be glad to continue helping you through follow-ups, if you'd like.
Third, I know nothing of skate boarding and whether the paints wear off from the shows, or how damaged the edges get due to the tricks the skaters do, and whether any of that is even significant in terms of coming up with the design; I looked into skateboard art and such, and it seems that unless the skateboard hangs on the wall for its life, being extra fancy is - extra.
So I'm going to approach this as a design that needs to be complete enough to sell.

I think approaching the design abstractly was a good choice; the chosen colors are excellent, and the shading is rather good as well. However, it is difficult to give a final opinion, because the bottom half of the design is not good enough in comparison to the top one, and it's hard to even accept that they're both part of the same drawing, and that the bottom one will be kept as is.

The solid black background is nice in terms of making the design jump out at you; I believe you should keep it solid. However, black as a color seems almost a bit too dominating- perhaps another color, just as cool and dark, but perhaps more towards blue/purple/crimson than black can be found? You could play with it; as long as it isn't tinted green or some earthy brown and such, I think it would fit and look good.

The text you chose for Forbidden is also excellent. Keep it. I'm sure that it can be integrated into the design even if you make the bottom half less smooth (or at least less smooth in more places).

Good reiteration of the red balls. It's creates good balance that you've repeated the blue used in the top half in the bottom, but the amount on the bottom is overwhelming. I'm sure you know this of the bottom half: it feels off stylistically, effort-wise, and color-wise. One hopes to see the pinks/purples of the right-top half reiterated on the bottom, and those curves of the shark/ship to be even more curvy.
The teeth certainly look cool. However, they're out of nowhere... Perhaps if the top half merged into the bottom in an Alien (the movie character, I mean) sort of resemblance, the teeth could be kept and would nicely draw attention...
They still do, certainly, but their surroundings (lack of detail) throw the impression off....
Actually, the shark/ship motif works, in a sense - there's something like cabin windows on the top right of the design, so the bottom half is not entirely out of place.
Simply - juxtaposition works only if it's radical... In this case, the bottom is not different enough to garner that particular effect. So it needs to be more similar to the top not to confuse the viewer.

Have you thought of leaving only two or three tiers of the bottom portion, rather than four? What if they started lower, maybe spawned a much smaller curve of bio-abstraction?

Also, in the top half, very close to the middle, there's a bit that looks very much like beginnings of the female torso... The diagonal it creates with the purple on the right makes it stand out, and makes it somewhat distracting... Also - the very middle, on the left, the tentacle thing that divides into four and hugs the blue - it seems to be of a dimmer, less intense yellow than majority of the rest you used...I think you should make it just as vivid as the other ones - it's not much of a change, but it'll increase the uniformity of the design.

I cannot pinpoint anything else that might need work; this would have been a terrific design, hands down, if not for the bottom half. If you ever change it, I really hope to see the result.


=MimozaBlooming