I wanna see Doomy get more airtime. He's such a fun hero, though I agree he's awkward to lane. You can't completely deny him farm, he'll always get at least 40+~40 gold on each Devour cooldown, but he's so easy to harass because of 0 armor and garbage agil growth. Seems like you really have to start him with Shield + Ring of Protection, but that means you won't have much left over for consumables. Just seems like an underplayed hero... Doom doesn't care about your BKB and disables items and most passive skills on top of silencing, and does significant damage.
Devour lets Doomy eat a creep and get a wide variety of skills, allowing him to be fairly versatile, and Level ? Death can be skilled at the right times for enormous, unexpected burst.
But I'm not sure where you'd put him in a lineup. He's not really that good played as a pure carry, not nearly as good as a Morphling or Anti-Mage or Spectre or Syllabear. Maybe he could be played as a support since he farms so easily (he'd be taking one creep away from jungle or lane per Devour cooldown, but that's not completely bad), but he really works best when he can get an XP advantage so he can make sure to skill Level Death at the right times, and so his Doom has a larger impact.