I have one, lvl53 warcry (8 skillers, +6 warcry helm, +3 warcry amu, 105+ fcr, around 2k mana and 3.5k hp, with lvl17 meditation on the merc), it's around 3k damage (not quite, you need lvl54 for that) so a bit less than 10k DPS.
If you play alone, it's viable, you are not the fastest but you are decently fast and you can have 1 point in find item for extra loot, you will have to ignore the inmunes tho, Visier can be kill "quick" enough with the venon proc on your merc's treachery, but Infector has way to high hp/poison resist for that and a Sunder won't help much since you can't lower their resist.
Insight is a must, even with 2k mana you will be potting like crazy without one and you are terrible killing bosses, so just skip them.
So in resume, it's decent for TZ with low inmunes, terrible for farming bosses and also very good as a support character in a party (I have lvl50 BO and warcry can stun wave 3 on Baal runs saving a lot of time).
If you want to level up using warcry be sure to have two spirit swords, 2 SoJ, Vipermagi and a low level insight for your merc, get as much skills and mana as you can (you will end with ~200+ points in energy priorize that) is going to be hard if you play solo selfound but again, it's possible.
D2:R