EDIT: Due to changes in Patch 1.0.4, WD pets have received major buffs. I'm updating my answer to include the new information on pets.
Pets are certainly viable in Hell and even Inferno. With the introduction of patch 1.0.4, pets receive a number of benefits that will make them competitive again:
- Increased base damage: gargantuan base damage is increased to 100% weapon damage, and humungoid, wrathful protector, and bruiser runes receive additional damage buffs
- Decreased damage from elite effects: pets and followers now only receive 10% damage from plagued, molten, and frozen effects
- Increased health: at level 60, gargantuans now receive an additional 50% of the player's maximum health; zombie dogs receive an additional 35% of the player's maximum health
- Decreased max damage received per hit: the amount of damage zombie dogs and gargantuans can take from a single hit has been capped, and the cap both scales with level, and decreases with the player's armor and resistances.
- General availability of the pets has been improved: Zombie Dog cooldown has been reduced from 60 to 45 seconds, Circle of Life passive has been buffed to give a 30% chance for a zombie dog over the old 5% chance, Tribal Rites now also reduces the cooldowns on Zombie Dogs and Gargantuan skills, and Grasp of the Dead's Death is Life rune now gives a 10% chance to spawn a health globe or zombie dog (previously it was 5% for a health globe)
The downside is that pets have a drastically reduced ability to proc abilities from gear, so pet-based crowd control and life on hit is no longer a viable main strategy (gargantuans can no longer proc effects at all, and zombie dogs have had two major nerfs to proc coefficients: rabid dogs went from a 1 coefficient to a 0.10, and burning dogs went from 1.0 to 0.05).
My original answer remains below:
Pet builds do appear to be viable, at least in Hell:
lv 58 WD here, zombie dogs are ok, i use them with the life leech rune along with my gargantuan plus the passive that allows them to take advantage of my life regen and thorns stats. They do last long enough for me to kill a huge mob, the only thing that kills them in a spilt second in hell is them dam elites and arcane sentries, and poison clouds. Just gotta have good items according to you level, high in armor vit and intel. btw let me know what you guys are rocking..
The issue is proper gear.
Contrary to rumor, Vitality does not impact pet health. However, Strength and Intelligence add armor and resistances. This makes a huge difference in pet durability. A number of people are claiming good results using builds with the Fierce Loyalty passive, stacking health regen to extend pet lifespans. Thorns effects can be stacked to add much needed damage to the pets.
Based on these discoveries, there is speculation that pets are viable through Inferno... with the right gear and build. At least one person claims to be using this tactic in Act 3 of Inferno:
Currently playing as a Minion Reflector WD in Inferno. Stack as much Life Regeneration + Thorn + Int gear as you can.
Left Click - Haunt + Resentful Spirit Rune
Right Click - Firebats + Plague Bats Rune
1 - Spirit Walk + Honored Guest Rune
2 - Summon Zombie Dogs + Rabid Dogs Rune
3 - Gargantuan + Restless Giant Rune
4 - Soul Harvest + Siphon Rune
Vision Quest / Fetish Sycophants / Fierce Loyalty
I don't have to tank a damn thing. Just stay back, haunt and spray. Reflecting 4k back on damage, and healing back 3k+ health per second which also applies to my minions.