pros:
-strong mid/late game.
-best farmer after singed
-big nuke to end enemies such as trynda,kyle,olaf....(the ones that can be a bore on low hp)
-aoe silence
-aoe knocked airborne and slow
-health regen (all the minions you kill with e)
-funny animation =D

cons:
-to easy to dominate over him early game if you know how
-no health regen if there are no minions around

early game will be a bit tricky especialy if you are in lane against an early game char.

start with boots of speed and 3 hp pots (hp pots are esential so u don't have to b if your enemy takes upper hand use them wisely)

don't let them near you till you are at least lvl 3 then you can probably kill most of them by combining exhoust and rupture. (always exhoust first rapture second if you do it the other way around the damage dealt to you will be much bigger)

don't let the enemy take you under your turret or not completly under his (if you get under his turret completly then the turret it self will farm a few minions, he will not be able to farm them all, which is not the case if you get them only half way there)

this is wery important early game try to hit the minions so that the enemy takes damage from vorpal spikes.

and last but not least try to rush malady after berserker's grieves tho wit's end offers you more dmg on paper mallady shreds their magic ressist (it amplifies MOST of the dmg u deal and will do later in game (vorpal spikes , feral scream , rupture ,malady......))

Upon reaching lvl 6 start using your ultimate , get your stacks up .
(you don't always have to eat champions)

also you might wana try ganking other lanes becouse they will not expect rupture out of nowhere.
(don't show yourself until you are sure your rupture will hit)

at this point you should have already bought malady and berserker's greaves if enemy teams damage dealt is mostly magic then go for wits end next, if not try to get madred's bloodrazor.

either way you should get both of this items and catalyst till late game (farming minions)

DON'T TURN YOUR CATALYST INTO RoA (you already have more or less enough health due to your ult try to get some magic ressist and armor + trust me you will do enough dmg without those 80 ap)

if the enemy team is heavy on disables you should probably want to take quicksilver sash instead of banshee's veil

this is the easiest part of the game for you .

try to catch as many enemies as you can with your rupture and feral scream.

also try to take down those nasty champs we were talking about by eating them =D
(trynda ,every carry in combination with kyle or zilean, ww, olaf and soo on....)

if you do not feel in need of more armor you should consider getting spirit visage
few minions and you do not have to go back and miss out on a team fight or nobody has to wait for you so you could do nashor few minions and we are good to go =D

I am using ghost exhoust in this build but that does not mean you can't take something else .

If my team already has a few exhousts i like to take surge it gives you nice bonus to your attack speed in time of need.

-always toggle off your vorpal spikes while hitting an enemy turret if there is a stealthed champion in game
(if not try to take down enemy minions with your vorpal spikes)

-if you are fighting champs like sion , ww , jax.... who have spells that get them on you and you are having truble throwing them away try to forsee it and throw rupture on yourself.
that way when you get stunned or snared or whatever you will not take that much dmg during that time .

-use feast on minions.

AND

-after eating and enemy always write /all nom nom nom nom nom =D