I wouldve thought it was a box more than a Z. But it looks really simplistic and nice

Mitochondria wrote Working the letter Z into a box is really not ideal.

Would recommend you fiddle around with illustrator, if you don't have a copy; there are ways. Mess around with shapes, and small vectors, you can make fairly basic stuff, look pretty good. You also have the flexibility of all of illustrators internals.

The sides are way TOO LONG, and the body of the logo is too thick, it really offsets the balance you need.

Bad criticism, asking someone who has just started doing logo's simple ones in-fact to use Illustrator which in it's self is very complex and which should only be used to make complex designs or for professional's, not someone who is using shapes to design a logo.

As my Good friend "Devil" Said the lines that make up the "Z" are not symetrical which take away from the design.