Debt service may be a better measure than debt unless one assumes some more or less constant reversion to a mean discount/interest rate. It is at least useful to consider the two, debt service and discount rates, separately. There are, of course, good debts and bad debts though the portion is adjustable through discount rates.
A borrower will look at it in terms of debt service. If it isn't rising neither they or their lender will be too concerned about repayment. If it is rising, they are either optimistic, speculative, or desperate, and the means to turn debt into equity, and the lender better know which, whether reasonable, and what the collateral is valued at.
A lender will look at it in terms of interest rate. Lower rates may mean increased wealth or reduced investment opportunities or increased risk aversion. If it is falling, borrowers are not borrowing enough and it is contractionary for the economy, but will lower debt service and allow the pursuit of lower return or riskier activities. In general I would say it is a case of dismal expectations or people would be investing in equity rather than debt, but perhaps not as dismal as feared, leading to better equity returns in the future.
Since no one is forced to borrow or lend, borrowing, in terms of debt service, must be seen as, a possibly unwarranted, but fundamentally optimistic act, and retreat from it as either the payback of a successful result or a failed one, but one must be wary of exuberance and despair, conscious of the investment being undertaken, and aware it can't grow without limit. A falling rate should be seen as concurrently negative but hopefully prospectively positive event.
Overall, the change is more significant, but the rate can change faster than the debt. Demographics, fiscal and monetary policy, risk aversion, or available investment opportunities may all alter preferred levels so the result can be difficult to interpret.
Is debt good though? Certainly the rate will determine whether it can be repaid or not, but ideally should the amount of debt change? I think not. Ideally, demographics are stable, the economy grows at a steady rate and offers a steady stream of investment opportunities and a steady return, and booms and busts don't occur. In such a world, there would be no reason for debt to change, but it isn't an ideal world. It might be rather boring if it were. What needs to be asked is whether optimism or pessimism is warranted or not. If not, debt should be headed in the opposite direction. Sudden changes may be necessary, but they are suspicious.