I love him post-patch and have played him even pre-patch. Even pre-patch he is purportedly strong up till +2k ELO. Unfortunately, I can't find any updated Pantheon jungle guides, but here is my favorite pre-patch:
What I have him do with the s3 changes:
- Start Machete with 5 health pots for faster clear time and jungle sustain.
- Get Berzerker's Graves with Furor. The faster atk spd helps proc his "block" more often, and furor helps chase down enemy champs, which works well with Pantheon since he has one of the fastest base movement speeds in the game. To get the Furor proc off better, be sure your combo is:
W shield bash > E heartseeker > AA > Q > AA... If you wait too long to do your heartseeker, you'll put too much distance between you and your opp, then you can't follow up with an AA to proc the Furor. Keep in mind his Q and W are single target attack spells, so that also procs Furor!
- Get "Spirit of the Elder Lizard" if your mid needs blue buff. The +50 atk dmg, faster jungle clear, and burn true dmg isn't too shabby either. Pantheon is very blue buff dependent, so mana regen is important. Pantheon is best with mid champs who don't need blue buff, like Katarina or Mordekaiser. You can still play Pantheon with a mana starved champ, but it will be harder.
- Get a fairly early Avarice Blade, but don't upgrade it till late game. Avarice Blade now builds into Atma's Impaler, which is a staple for many Pantheon builds.
- Emphasis Phage early. Due to Furor proc, your ability to chase alongside Phage procs will be ridiculous. Don't be afraid to dive a tower to finish off a weak opp either, since keep in mind your W shield bash blocks the first turret shot.
- When ganking bot lane, if they have sightstone, just assume everything is warded, lol. The only viable gank bot is via your ULT or sneaking into bottom bushes via your team's lane. Due to the added difficulty of bot ganks, I'd avoid ganking bot pre lvl-6 and concentrate on top and mid. The exception is if the enemy is pushed heavily into your bot's tower, in which case all the vision in the world may not save them.
- Pantheon is still ridiculous at lvl 2 ganks with his Q spear shot and W shield bash. Don't let the starting Machete deter you.