Mara Liasson had a report on NPR this morning about next year's Senate elections (can't find a link). She definitely makes it sound as if the R's are in a great position to take control of the Senate.
Here's the skinny. Democrats now have a 54-46 advantage. Democrats are retiring in three states—West Virginia, South Dakota, and Montana—where the Republicans seem poised to pick up. Those three would get them almost there, and they're pretty much givens (possible exception is Montana, depending on who runs).
The other best chances for Republican pick-ups are four red states where incumbent Democrats are fighting to keep their seats: Louisiana (Mary Landrieu), Arkansas (Mark Pryor), Alaska (Mark Begich), and North Carolina (Kay Hagan). If the R's pick off two of those, which can certainly happen, they get to 51.
But that's provided they don't lose any seats. The math there just changed yesterday in Georgia, where Sam Nunn's daughter Michelle just declared to run as a Democrat. The leading R's are way out there. If Nunn can win, that's a bit of a firewall. Then there's Kentucky. A McConnell loss has to be considered a longshot at this point, but at the very least it's going to be a high-profile race against an incumbent who isn't exactly adored.
I'd say the R's will get close, 51-49 or maybe even 50-50 (in which case the Democrats keep control because the vice president casts the vote that breaks the tie). But if the R's do take over, while holding the House, then we're in for an awful two years, no matter which side you're on. The only silver lining I suppose is that the Republicans wil behave so awfully in 2015 and 2016 that Americans will punish them that November.