Looking for constructive critique

I really like the graphic in the back, excellent visual of what you do. I don't know if the airbrush is necessary, it looks to be cluttering up the right for me. Also, I might play with the font for 'custom paint'. maybe choose a font that isn't so expanded, that way you can have a looser kerning and might cut down on the sense of clutter. Then again, the expanded font provides a nice strong foundation for 'adshadow'.

Lol, alot of help I was!

P.s. can you make the margins just a tad bigger, the information seems really close to the edge.

I don't like the "M" sitting in the socket.
CUSTOM PAINT is too tight to Madshadow and too big.
The airbrush is really cramping up an already cramped up area. Try having it clamped in one of the skulls jaws or sticking out of a socket or dropping it altogether as the name and visual says it all. Once the airbrush is out of the way, reduce the text size and flush right the website...you're cutting off some excellent airbrush work...that's one tool I could never feel comfortable with.
Sorry...the photo on the back isn't doing it for me. I'd source a more dramatic shot or do a before and after treatment to show your potential client what you can do to their bike.

My only problems with the front would be little nitpickety things...

Put one phone number and the web address on a single centered line on the bottom, remove the city/state and owner/artist. Then give the name a little breathing space by moving it and the airbrush down a little. But for an airbrush artist - this is serviceable font work, imho.

The backside is not even in the same league - fonts tossed onto a photo. I'd run that as a separate card next time.

I'm thinking you don't even need the airbrush at all. Just move the background a scrunch to the left to get the M out of the eyesocket, and I like it. Nice work on that side.

The other side doesn't even look like it came from the same company. Doesn't match at all. Like suggested before, move that info to a separate card.

CARD:
the grid could be "free" not so "adjusted to margin"
don't like spacing between text lines
I hate all back
LOGO:
don't like "CUSTOM PAINT" font & height

The airbrush isn't doing anything for you. It could even be construed by the clueless as a high-tech hash pipe.

The front and back don't really match, do they? They strike me as two separate cards.

I agree with Mama that having the lower left edge of the capital M right in the center of an eye socket is distracting and unpleasant. I would reduce the size of "Madshadow" just enough to clear the socket entirely.

I'd like to see a nude, skull headed, sword weilding woman riding a hellish wolf with flames shooting from it's mouth as your logo. Seriously, I would!

Let the art be the message. No need to explain. The genre is so well defined, an illustration of your own creation with your name/number is all we need to know who you are and what you do.