Not necessarily...off the topic of my head i can come up with a couple of builds that it can benefit:
1) Blade Fury Sin (actually i think the ed will help, just not much)
2) Heh...tha's all i got for now, but basically any class that uses proc skills without attacking with the lash
Depends on your playstyle, and the ruleset you've chosen for yourself. If you're playing untwinked, sinlge clears with a fanatic zealot and that drops on your way to kill Baal, it would have to be the most useful drop I could imagine.
If you are playing a MF sorc who is running Meph twice a minute... the weapon is really really pointless.
Neat thing about D2... people play the game as it suits them.
I was able to smite with a zero durability (non-eth) Stormlash on my hammerdin. The durability counter read zero but it wasn't redded out, and I could unequip and re-equip it just fine. When I equipped it, it still showed up on my character model and I still got the CB and CtC static when using Smite. If I landed an attack with zero durability Stormlash using something other than Smite, it'd break immediately; it wouldn't show up on my character model, I'd lose the stats, the durability would show in red, and once I unequipped it I couldn't re-equip it until it was repaired. So it seems like as long as it hits zero durability while you're using it for Smite, you can continue using it for Smite as long as you don't use it for anything else.
Edit: Not that there's any particular benefit to using an eth weapon for Smite, but if you don't have a regular Stormlash then knock yourself out.