I recently bought a 1998 Jeep Grand Cherokee from a dealership. When we bought it, I noticed that the brakes were not working very well, and the dealer fixed them before we finalized, putting in a completely new system. However, my wife, who is the primary driver of the vehicle, has been complaining almost from that very day about squeaky brakes. I'm not wanting to take it anywhere, because I know the brakes are fairly new. How much of a concern are squeaky brakes?
It's not a concern really other than being annoying if in fact the brakes are new. It's not a difficult fix; just putting disk brake quite on the back of the pads should solve the problem. It should have been done when they did the brake job, so I would take it back to the dealer where you bought it and ask them to fix it. At my place it would be done at no charge to you if we had just done the brake job.
It's worth noting the brake squeal this question is referring to is when the brakes are applied. Brake squeal that goes away when you apply the brakes and comes back when you release them is the wear indicators meaning that your brake pads need to be replaced.
Sometimes a loud noise or high pitch squeal occurs when the brakes are applied. Most brake squeal is produced by vibration (resonance instability) of the brake components, especially the pads and discs (known as force-coupled excitation). This type of squeal should not negatively affect brake stopping performance. Simple techniques like adding chamfers to linings, greasing or gluing the contact between caliper and the pads (finger to backplate, piston to backplate), bonding insulators (damping material) to pad backplate, inclusion of a brake shim between the brake pad and back plate, etc. may help to reduce squeal.
It could also be that the dealer didn't apply brake grease. Brake Grease does NOT go between the pads and the rotors (where the friction occurs that makes the brakes work), but between the pads and the brake cylinder inside the caliper. It also goes on the little metal clips that are on the side of the brake pads. Often, squeaking in brakes is caused by the movement of the brake pads inside the calipers - and so lubricating this will prevent squeaks.
Some brake pads are designed to squeal when the pad material is worn down to a certain point, the idea being that the squealing will warn the driver that new pads are needed. This isn't your problem, because your brakes are new, but it is one answer to the general question, "Should I be concerned about squealing brakes?"