Cryo is heavily misunderstood by both it's supporters, and even more so with it's nay sayers.
Will it improve groupings. Yes and no.
Cryo does not change the physical dimensions of a barrel. There fore, your gun will not shoot smaller groups, nor will it shoot worse unless the cryogenicist messed up some how. You can air gauge a cryoed barrel before and after, and unless something went wrong in the process, you will have the exact same results.
What it does do is strengthen the molecular bond and relieve internal stress. The number one benefits of cryo are less molecular deformation caused by heating, outside stress, and internal molecular stress. It also reduces wear on areas that see contact from other objects.
Heat Deformation.
Heat deformation is a very common problem with accuracy. As the metal heats up, it literally softens, causing the barrel to deform easier. When the molecules heat up, they tend to lose their composure and bond, causing the metal to be more prone to said unintended movements. Cryo strengthens these bonds, so the barrel will keep it's accuracy longer during shooting sessions. Basically, your barrel will hold it's accuracy longer while you shoot. This is considered to be the number one benefit of cryo treatment.
Outside Stress.
This is a force applied to the metal object by a foreign source that causes unwanted consequences. Picture a bullet traveling down a barrel. Each time a bullet passes down the barrel, force is applied to the structural form of said barrel. Cryogenics will help stabilize the barrel when such forces are applied. This is believed to be a minor gain opposed to others.
Internal Molecular Stress.
When an item is forged, the molecules of the object are literally forced into place. As with all force shaped metals, they have a tendancy to attempt returning to their original shape. For instance, picture a spring and the effects of what happens when you compress it. Heat is a major contributor in this process. Again, increasing the molecular integrity of an item will help lessen the likeliness of an object to do so. The molecules in a forged item naturally fight themselves. Heat treating is a major factor, but Cryogenics have shown very positive results when relieving internal stress as well.
However, some barrels may not benefit from cryogenics at all. When a barrel is made absolutely right, the effects of cryo may never receive the chance to prove themselves. Luckily for the cryogenics industry, a very minimal amount of barrels are manufactured to such standards. Cryo does have it's benefits, but most slow firing bench shooters won't be able to tell a difference. Some people go out and fire one five shot group and expect to have their groups cut in half. It doesn't happen, so they hold a grudge against money they paid for a service that may never benefit them.
So it's up to you to decide if cryo is worth it. Your barrel should last longer, and you should be able to hold your groupings longer while shooting. I haven't cryoed a barrel, as I don't feel I'll ever need or use it's benefits.