A logo can be an important part of your business. It can give a first impression and should reflect what your business does in some way. Many people get too carried away with their logos and end up with something that is miles away from the ethos of the company.
You need to also consider how and where it will be used. If you often use your logo on literature for example then you should see what it looks like shrunken down as well as enlarged. If you are going to have text on your logo, you need to check that it will still re readable. Some companies chose to have two variations one logo with their company name on, and the other more of a symbol (part of the logo) that can be used when needed in a smaller format.
Consider the colours that are within your logo and check that it will work well on white and black backgrounds or any others you think you may use.
Do not be afraid to go back to your designer if you are not happy with the logo they have come up with as often they may just need a bit more guidance from you as to what you want.