I do it from time to time in normal games. I don't know how viable it is, but it's certainly doable.
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There's his taunt, which is a strong engage tool (also, the movement of the champion backwards as opposed to stuns/roots in nice for the jungler)
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He get's a free decent dmg harass/trade from his passive
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He has a shield to soak up dmg
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He can ult from base, which opens up a lot of opportunities for global plays, including strong counter engage, baits by "alone adc", guaranteed full health tp to lane (twice if you take tp over flash)
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Despite being melee, he has a nice harass tool (his q)
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Mana-less sustain champ who can practically live in lane as opposed to other supports
But what I love most about, and what people tend to overlook, is that his sustain can be shared with the ADC via the passive on his Q to marked targets. This allows ADCs to essentially farm their health back from minions and possibly ease trades into your team's favor. The passive from his q also scales with Shen's health, synergizing really well with existing support items (ie. Ruby Sightstone, Face of the Mountain, early giant's belt for Randuins/Warmogs)