A resounding yes! Whatever your relationship and no matter how long or short a time you've been together; there will always be points that can improve.
It can help with all issues, big or small. It's not the last resort for a relationship that needs a complete overhaul. Major issues of course are a real reason to consult a marriage counsellor. Things like abuse and infidelity are easily thought of as legitimate causes that require the intervention of a therapist. What people often overlook are things as basic as working towards good communication skills and compromise in a relationship. Therapy can help a couple overcome some of the smaller hurtles before they become larger stumbling blocks in the partnership.
An objective point of view can often offer some insights into your relationship. It gives you the basic tools to make your relationship better. Sometimes a problem has been around for so long that it just becomes part of the relationship instead of a problem that can be overcome. Managing conflict, stressors and frustrations are all skills that can be honed with the help of someone who is trained to see the dynamics of the relationship.
It can help you learn about you. When it becomes easier to spot how you react to certain situations; you can better learn to solve the issues as they arise rather than sweeping them under the rug or blowing a gasket after you've finally had enough.
Therapy can teach you to be proactive about problems; before they actually become problems. The differences that attracted can also drive a wedge between a couple. How you deal with it helps decide what's a problem and can cause your relationship conflict down the road.
Perfection in a marriage or relationship is nothing short of looking at life through a pair of "rose-coloured glasses". It just simply does not exist. Looking at the time and emotion invested in a relationship makes it worth the decision to take a second look and make a good relationship better.