ORIGINAL: VF84sluggo
It has been a looong time, but I vaguely remember my Aero 201 professor talking about the eliptical wing of the Spitfire being an almost ideal wing planform. The lift distribution smoothly tapers from root to tip, especially as the lift coefficient is increased. The eliptical shape also minimizes drag from losses at the tip (wingtip vortex). So, an aerodynamicist loves it.
RC
Yes, it is not a good choice for structural strength. I seem to recall that the elliptical tips did stall at the tips easily.
The elliptical tips on propellers are a good thing to have over the squared off tips in terms of prop efficiency and noise.