OP: I've tackled this problem in my own writing...I started out wanting to write my story from third-person and ended up doing it first-person at the last minute. Reason; it felt much more natural and it suited the genre I was writing in (detective fiction).
My take; if you are even asking this question, go first-person. Also; if the story seems to want to be humorous, work with that...don't fight it. If it feels amateurish, that might be a character voice rather than a flaw. If it is consistent people might like it. Write it out and see.
Example from my own work; I chose to write a noir
novel from the perspective of a female private investigator. I would come to places where I could not think of an evocative way to describe what was happening...so I just put some bare bones in with the idea of fixing it later. This approached ended up netting a no-nonsense, tell-it-like-it-is narrative beta readers found fresh and interesting.
Granted, it took a few chapters to settle out that way but by the end I had it working.
Short answer is write it out and see, and don't fight your inspiration.
(Note: third-person narrative does have its merits, but I've found that by nature it is more dry and distant. Whereas first-person is up close and personal...if and only if your character is well-developed enough to keep the reader coming back for more.)
edited 20th Jan '13 8:33:52 PM by drunkscriblerian