Generally fiber reinforced concrete is comparable to non-fiber concrete with wire mesh. The shrinkage cracks are fairly common and may not be a problem if they are not very wide. You can use a self leveling polyurethane caulk to fill the crack. If you experience a great deal of cracking, the concrete was not done properly or the sub grade was not prepared properly.
One problem that occurs all too often is that a concrete finishing crew will add water to the concrete after it has been delivered to the job. This in itself is not the problem however. The problem is that they have a tendency to add too much water. While wetter concrete is easier for the finishers to place, it will shrink more as it dries causing shrinkage cracks. The stiffer the concrete the less shrinkage you will experience and the stronger the concrete will be.
There is a test used for concrete as it is being poured called a “slump test”. It is used to tell how wet the concrete is as it is being poured. A metal cone is inverted and filled with the mixed concrete before it is placed. Then the cone is carefully removed and the distance the concrete slumps is then measured. The further it slumps the wetter the mix. Concrete for a building slab should not be more than a 4” slump. A slump between 3-4 inches is preferred. Most residential contractors do not have this test performed on concrete they use even though it is a simple and inexpensive test that would save many homeowners a great deal of aggravation. The reason many do not use this test is the finishers complain the concrete is too stiff to place easily making their job more difficult. The more difficult their job the more money they will ask for doing it.