Why this is good for Democrats- Without a 60 vote majority in the Senate, Republicans will be able to obstruct by themselves and that might backfire when nothing gets done in the next 10 months. It also means anything that passes will have to be bipartisan (if only with one or a few Republicans).
Why this is good for Republicans- Republicans are more enthusiastic right now and this is another piece of evidence that that's the case. With the ability to obstruct in the Senate, it's going to be hard for Democrats to look like they've gotten anything done in the last 4 years as the majority.
Why this is good for America- Most Annoying Senator in the World Joe Lieberman is now vote #59 not #60 so he'll have less influence and get less attention.