Contract still valid? Should I still have to pay?

I hired a gentleman to do some work on my house. He had me sign a very basic contract that included the work he was doing and the cost it would be. He requested a down payment, which i gave him. We verbally agreed that he would have the work done in 2 weeks and would be paid the remaining balance after. Long story short, the gentleman was missing more than he was working. It took him over 3 months to finish the job. Am I legally responsible to pay him the balance even though the job exceeded the agreed timeline? and Is the contract even valid after this long length of time it took to complete the job?

Ultimately, no one can comment on the enforceability of a contract that we haven't read.  The best that we can tell you is to have it reviewed by a local attorney. 

What happened between the 2 weeks and 3 months?  Did you contact him? 

You say it took him 'over 3 months to finish the job.'   Since he 'finished' the job and you did not complain during that time, you likely owe him.  Obviously, you made no attempt to stop him from finishing the job--even though it took longer.  

It would seem therefore that you owe him.  A lawyer will likely cost more than it's worth to haggle.  If the work was satisfactorily completed, you owe him.

I agree with Carol.

You basically LET HIM take three months.

Pay him.