Disadvantages

I will list the disadvantages here as I 'discover' them.

•  It is not paint. If a paint job is done professionally and buffed/polished to perfection, vinyl will lose a side by side comparison. 
• It will not last forever (which may be an advantage...time will tell). Long term durability is still unproven and is not well known for airplanes stored mostly in hangars. (5-7 years for auto wraps).
• The same amount of preparation is required for vinyl wrap as for paint as vinyl wrap is essentially colored shrink wrap in application. It is as unforgiving of dings, smileys, etc. as is paint. It shows most everything except for fortunately pin holes.
• Although my RV-8 is stored in a hangar, ease of removal after baking in the sun for 5 or 6 summers is an unknown.
• Compound curves are problematic, read hard to do without stretching the vinyl beyond breaking point.
• You need to order sample sizes to get the right color you want as your computer monitor distorts the true colors. The blue vinyl on my home page is actually much darker than it appears.
• Sensitivity to fuel. Not necessarily the top that you see, but underneath where it attacks the sticky substrate. This does however make vinyl an excellent fuel tank leak test method...see advantages.
• Sticks best to paint and bare metal. OK to smooth primer but not to glazing compound, textured surfaces, and leaking (fuel) rivets.
• If you want to avoid easily seen seams and edges exposed to the wind, you need to plan your layout so that your seams are hidden (at least not obvious to casual glance) and that forward pieces overlap aft pieces.
• Some areas will still need to be painted such as exposed hinges, bearing brackets, rear spars, etc. 
• You will be going where few builders have gone before.
• Builders who have invested thousands in a professional paint job will naturally feel compelled to deride a vinyl wrap that costs hundreds.