It is not electronic, but it is far more than a magnifying glass. The high end viewfinders are just as complicated optically as the lens in from of the camera. (And just as fragile.) The standard housing viewfinder is nothing more than a single lens to move the focal position back to where your eye should be with a mask.
After using an enhanced viewfinder I would find it hard to go back to the standard housing viewfinder. To chose between a 45 dgree or a straight viewfinder is really personal preference, though I have listened to convincing arguments that the choice is 45 degree for macro and straight for wide angle. I wish I could afford both for comparison.