I think for Bush it was his best debate so far but at single digit in the polls it won't make any difference for him.
Carson was at the bottom I think the overall loser. I don't see any big moves. Trump and Cruz will remain at the top.
It almost seemed that Cruz and Trump has a pact not to attack each other? On the other hand Rubio it seemed was under constant attack.

GOP debate winners and losers

http://thehill.com/homenews/campaign/263393-gop-debate-winners-and-losers

The final Republican presidential debate of 2015 brought heated clashes between several major candidates in Las Vegas on Tuesday night, when national front-runner Donald Trump tangled with a newly assertive Jeb Bush, and Marco Rubio and Ted Cruz repeatedly jabbed at each other.Who won and who was left licking their wounds with only seven weeks — and one more debate — left before the Iowa caucuses?

WINNERSFormer Florida Gov. Jeb BushBush had by far his strongest performance in any debate to date. The former Florida governor, whose last election campaign was in 2002, had looked rusty and hesitant in all his previous outings. On Tuesday night he made a far crisper and more assertive showing. Bush delivered the most memorable line of the debate’s early stages when he said Trump was “a chaos candidate. And he’d be a chaos president.” In a later exchange, he told the businessman, “You’re not going to be able to insult your way to the presidency,” a phrase met with applause from the audience at The Venetian casino hotel. There were important caveats to Bush’s performance. He didn’t win every tussle. The awkward, fumbling Bush on display in the first four debates suddenly reappeared when it was time for a closing statement. And the biggest question is whether a good debate can really help a candidate who languishes at just 4 percent national support, according to the RealClearPolitics polling average.Still, Bush's supporters can take heart. The candidate they’ve been expecting for months finally showed up on Tuesday evening.

Sens. Ted Cruz (Texas) and Marco Rubio (Florida)
The two senators have been on the rise in recent polls — Cruz more dramatically than Rubio — and each man seemed to keep his momentum going. The two punched and counter-punched throughout the night on subjects including government surveillance, military spending and immigration. The exchanges were often sharp: Cruz repeatedly accused Rubio of sowing confusion and even invoked the name of left-wing organizer Saul Alinsky — a much-hated figure among conservatives  — when describing the Floridian’s tactics. But Rubio stayed on offense for the most part, and Cruz did himself no favors by at times attempting to talk roughshod over rivals and moderators.

 The senators ultimately fought to a draw, and the fact that their jousting took up so much airtime underlined their status as the candidates on the rise, right behind Trump.

New Jersey Gov. Chris Christie
Christie, who was once written off in this year’s race, is now a serious contender in New Hampshire, at least. His impressive performances in debates have helped fuel his resurgence. Tuesday was not Christie’s best night at the podium, but he acquitted himself well, especially when he contrasted his executive experience as a governor with the work of the three senators onstage, whom he disparaged as talkers rather than people of action.On the subject of guarding against terrorism while also not infringing civil liberties, Christie exhorted the moderators to "talk about how we do this, not about which bill ... these guys like more. The American people don't care about that.”

MIXED Businessman Donald Trump

Trump’s instincts for how to make news are unerring, and he proved that again with a declaration in the debate’s closing stages that he would not make a third-party run for the White House if he failed to secure the GOP nomination. That alone will ensure that the national front-runner wins his share of headlines in the aftermath. But it was otherwise an indifferent night for Trump, who encountered more audible hostility from the crowd in Las Vegas than he has during previous bouts. Trump’s disdain for details has long disconcerted political professionals, and it manifested itself again in a confusing answer about whether he would seek to restrict Internet access as part of the battle against radical Islamic militants. But Trump’s “broad strokes” approach has not harmed him so far, and there is no reason to assume it will do so now.

Sen. Rand Paul (R-Ky.)

Paul only made the main stage for this debate by the skin of his teeth, but he made adequate use of the opportunity. The moderators’ focus on foreign policy and national security helped Paul in one sense: He got the chance to expound on the libertarian-leaning beliefs that are the bedrock of his politics and to express his skepticism about military action. “We have to have a more realistic foreign policy and not a utopian one where we say, ‘Oh, we're going to spread freedom and democracy, and everybody in the Middle East is going to love us,’ ” he said in the late stages of the debate.

“They are not going to love us.”The problem for Paul is twofold. First, however polished his arguments on these issues, there is no evidence at all that a plurality of Republican voters agree with him. Secondly, he is likely just too far behind — he averages around 2 percent support nationally, according to RealClearPolitics — for even a positive showing to make much difference.

LOSERS

Retired neurosurgeon Ben Carson

The halcyon days of Carson’s presidential campaign look as if they could be over. His poll ratings have been dropping precipitously in recent weeks, since terrorist attacks in Paris and San Bernardino, Calif., raised questions about his grasp of foreign policy. Carson’s debate style has always been unorthodox: soft-spoken and affable to his supporters but vague and meandering to his critics. That was acceptable when he was soaring in the polls, but it’s hard to see how it can possibly turn around his recent decline.

Ohio Gov. John Kasich and businesswoman Carly Fiorina

Neither Kasich nor Fiorina had any real flubs. But they both needed something extraordinary to vault into serious contention for the nomination. They didn’t get it. Both candidates were marginal figures for long stretches of the two-hour debate.