Like anything, there are pros and cons:
Pros: one spray point, no boom out there to hang up on brush or break, you can spray areas you cannot get to.. along fences for example,
Cons: sprays up into the air, thus more drift than with a boom, more evaporation, more sensitive to wind velocity, coverage is a little less even than with a boom.
Net: They work fine. I have both a boom and single point nozzle sprayer like you are talking about. In reality, there are several nozzles on that single point. They point in a fan so that the spray droplets are sized for the distance they are going to travel. Bigger for farther travel to the side, smaller for closer in.