It may be an advantage right now because his opponents can't rip him so easily on policy when they don't know his full policy right now, but the inability to define policy will trip him up sooner or later.
That's why I thought the question about small business should have been aimed at Trump because, well, DOES he have an answer to that?
Okay, I see the issue with the conversation here. You've come to think of Trump as a long-term candidate; by that standard, he underperformed. I see Trump as a glorious media maelstrom made manifest - the human form of a perfect storm of all the sins of modern media and what it represents, does, and creates - and by that standard he did pretty well. We need polls: his candidacy hinges entirely on support from the grass-roots, since he is largely immune to party elites' concern about electability (largely because he already alienated them).
I sense that this debate did not change the standings as much as people expect it will. The thing to really watch, I think, is how it will affect candidates at the bottom: the effect of the debates can be overstated, but when you are polling single digits, any swings are huge. Carly Fiorina, I hear, did extraordinarily well in the second-tier debate, so maybe we'll see her next time. Carson was so thoroughly under-performing in the polls that his strong showing here will be a huge shot of adrenaline into his feeble campaign. Christie is a wild card, but I don't think he came off all that well; of course, people were on the verge of forgetting him entirely, and any attention is good attention. Kasich seemed fairly positive, considering. I think Rand Paul did well in his faction, but poorly among people who aren't inclined to support him. I don't know how Huckabee will be received.
We need time to let it stew. A few internet polls (as reliable as those are) on the winner have been pretty consistent: roughly one third picked Trump, with Carson following behind.