Buying a house is this crack cause for concern?
I have looked at something like ten houses with cracks in the brick. In the U.S., most brick houses are veneered brick, as opposed to structural brick. Veneered brick can crack in a manner similar to the crack you presented in the photo for a number of reasons:
1. Foundation settlement. Evaluation of foundation settlement requires a structural engineer with a precision surveying instrument. An initial evaluation only rarely determines if the settlement is ongoing, usually you have to install a strain gage (sometime called a crack meter) to monitor movement over time.
2. Improper detailing of the attachment of the brick to the structural wall. Sometimes this is caused by lack of brick ties, use of an improper brick tie, inadequate number of brick ties, or deterioration of the brick ties. Evaluation of this issue almost always requires accessing the cavity between the stud wall and the brick, assuming there is a cavity. This is invasive surgery, hard to do on a house you do not own.
3. Improper brick type. As amazing as it seems, I have run across houses that were built with interior brick rather than exterior brick. This can cause a variety of issues.
4. Improper mortar type. Most of the portland cement mortars are stronger than the brick, unlike the old lime mortars that were in use for thousands of years. This can lead to cracking of the brick due to temperature fluctuations in the brick veneer due to solar gain. The temperature fluctuations cause the mortar to expand at a different rate than then brick, and if the mortar is stronger than the brick, the brick can crack. If the mortar is poorly adhered to the brick, the mortar can crack instead.
There are other causes of cracking that are less common. The only way to make an intelligent assessment is to hire a local, competent engineer or architect familiar with brick problems. This of course is not a free service, and in my opinion cannot be performed by the average home inspector. If this house is not of sufficient interest to you to warrant spending money on a professional investigation, I suggest you walk.