I'm surprised to be among the first to comment on this, it's a really awesome piece and it's probably just the case that people are generally very much in awe of it's awesomeness!
There's a lot that I like about this, the design of the freaky creature (or whatever it is!), the atmosphere, and the simple yet effective casing/shelving around it .. it's really got the feeling of having been there a long, long time.. and also of it seeping/breaking out of it's container... perhaps to quietly infect (maybe even poison?) the world around it.
The composition is great and feels natural, more like a photograph than a painting, like a snap-shot of some weird oddity on a shelf in some forgotten museum of horrors somewhere. The subject makes a heart shape, suggesting a subtext of emotional disconnectedness, or forgotten emotions/relationships.
I also like that I can see the mix of styles here, both yours, Zdzislaw Beksinski's and maybe even a bit of Giger too? It all knits very effectively together, I must say.
All in all there really isn't much I dislike about this piece mate, an Oubliette may be (as Hoggle says in the labyrinth) "a place to put people to forget about them", but this is certainly a painting to remember!
Congrats and thanks for sharing!