What trade-offs are being made in the design of the planform alignment of stealth aircraft? Stealth technology uses angles in the aircraft shape, and homogeneous orientation of the surfaces. In the F-22A Raptor wing leading edges, tail surfaces, air intake bypass doors, refueling aperture, etc have the same orientation.



Incoming radar waves are deflected in a different direction, giving the enemy the impression that there is nothing there.



However, as mentionned in Wikipedia: "Shaping requirements detract greatly from an aircraft's aerodynamic properties. The F-117 has poor aerodynamics, is inherently unstable, and cannot be flown without a fly-by-wire control system."

I'd like to know what are the impacts of such planform alignment on planes capabilities, and how does a passive stealth shaping, using a small number of surface angles, compare to a "5th generation fighter"

This is a different question than Do similar angles on a plane make it more stealthy?" I'm looking for the advantages and disadvantages of using planform alignment.
To understand the functioning of planform alignment in befitting the fifth generation air-crafts in increasing their stealth, one first need to understand how Radars work:


Radar transmits a radio wave signal.
This signal when comes in contact with a surface (of an aircraft), it is reflected back. This reflection is a mixture of Specular and Diffused reflection. 
The radar then after receiving the reflected signal, measures the speed (by computing the shift in the time period taken by the wave to be received over a period of time), and size (by computing the intensity of the reflected wave) of the air-craft.


But there is a problem, since the radar needs to get back its own transmitted wave back, if it is reflected off the surface of the plane only at a specific angle (specular reflection), then the receiver of the radar needs to be at specific places to receive the reflected wave. 

Modern planes utilize this shortcoming of the radar by letting the incoming radar signal pass through them (using plan-form alignment), which then greatly reduces the reflected signal. The reduced reflected signal would be seen as an incoming signal of very low strength (intensity) by the radar, which then reads the size of the incoming air-craft as a very small object. This is called Stealth. The air-crafts also use special paints and composite coverings on the surface to again reduce the intensity of the reflected wave, to reduce the percieved size of the air-craft by the radar.

The shortcomings of such radars are removed by using radars such as AWACS, which is moving radar and can receive too directional signals (Specular reflection). Or, using radars such as AESA, which scans a large portion of area around it without having any moving parts.