Even inexpensive cabinets can look great if they are properly installed and vice versa. Kitchen cabinets should be installed with proper planning, care and skill to get that crisp and high-end look.
A good installer will make sure that cabinets are properly secured by screwing them to studs. Cabinets that are not properly installed will overtime shift causing unsightly gaps and may start to appear leveled. If base cabinets are not leveled or properly shimmed, overtime due to the countertop pressure may sag or crack. Stone countertops are prone to cracking if base cabinets are not properly leveled and secured.
Please be very careful of contractors who are charging you below market price for installing kitchen cabinets. Please make sure that your contractor is well qualified to install cabinets.