First, to briefly address the border issue: both sides want an open border. Both sides also accept that an open border requires the rules on either side, with respect to customs arrangements, to be the same. The UK wants to set its own rules. This necessarily creates a contradiction -- one that the UK is perfectly entitled to create, but is responsible for all the same. So far, the only ways to resolve this contradiction rely on either as-yet nonexistent technology or the UK acting as a de facto tax collector on behalf of the EU. Understandably, the EU is not keen on relying on us to collect its taxes. In any case, this problem arises entirely because of the UK's decision to leave the EU, and then to try and rush through this without sorting out the practical details. Blaming the EU for merely pointing out a logical contradiction is misguided.
Returning to the original question: No Deal entails all sorts of different things depending on the preparedness of both sides for the failure of negotiations. As far as I can tell, both sides understand this and have contingency plans in place, or are in the process of setting up these contingencies, so the worst-case scenarios of No Deal are likely to be avoided. But it's hard to say specially what the implications are.
One thing that may help the UK is that, being a separate country, it will at least have the liberty to act unilaterally in responding to crises as they occur, whereas the EU is obliged to consult all countries on interim arrangements. On the other hand, in percentage terms the UK is more dependent on EU trade than vice versa.
I suppose I should have just stuck to "I don't know, but probably unpleasant". It's in both sides' interests to avoid a no-deal, but that doesn't mean that either side should accept any old guff instead.