Um. Its really not good, even considering its your first, sorry.
A lot of the details are extremely out of preportion in size, including the horns on the med helm and symbol on the chainmail (what happened there???).
I'm pretty sure you tried to make it look like he was stepping towards you, it kind of just looks like he has a abnormally large and long leg. To somewhat fix that, you should add some detail in the leg to make it show as if it was bending.
The shading is really just as bad. It makes no sense where you put the reflection and shade on the metal. Its not realistic at all.
The colors dont compliment eachother at all. It seems as if theyre completely random and you used the default colors in the Paint toolbar. Example: One arm is a different color than another... with yellow shade

.
Also, for some reason only some of him is outlined in black. That makes no sense, either outline all of him or none (Personally, I suggest 1px black outline).
A good backround would help make it look more realistic. It doesn't seem as if you put more than 30 minutes into this. Pixels take a extreme amount of work and time to be good. You can't rush them or you'll end up with.... this.
Don't stop pixeling, youll get better as you progress, sorry for being so harsh

, but im just trying to help. I suggest you look at the pixels by this artist, they're good to look at and learn from:
http://s15.invisionfree.com/misterxman/index.php?showtopic=1
Good Luck and All the Best,
Pr0