First, check what kind of lease you signed. Depending on the terms of the contract, you may be able to get out of your lease by the time it expires. It can also help answer whether or not your landlord can refuse to accept your lease termination.
In terms of maintenance, as a rule of thumb any major repairs are required to be fixed by the landlord, while minor ones (light bulb changes, etc) must be handled by the tenant. If the issue is in a common area or hallway/stairway, the landlord MUST fix ANY problem within a reasonable period of time. Depending on the nature and severity of these infractions, you may be have a case against him that would free you from your contract.
If it comes down to it, you can try throwing your weight around, but honestly, I would highly recommend bringing this situation to his attention before you bring formal action or threats. If you can't beat him in court and he doesn't want to let you out of the lease, you can always sublet the apartment. You're perfectly within your right to do this and the landlord has no legal way of stopping you.
Hope this helps! Good luck!