between between 0.43 °C and 0.71 °C warmer than the long-term (1961-1990) global average of 14.0 °C, with a best estimate of around 0.57 °C.So how'd they do? Just a little high. The actual 2013 global average was 0.49 °C.
Like all measurements that number has an uncertainty, which comes from the uncertainties of each monthly number. The Met Office conveniently gives those every month, in the last two columns here. They're actually not that small -- typically about 0.15 °C for each monthly anomaly (2-sigma) -- and when I include those the way you're taught in undergraduate lab[*] I get an uncertaintly for the yearly average of ± 0.05 °C.
So the actual temperature[**] was 0.49 ± 0.05 °C compared to a prediction of 0.57 ± 0.14 °C. That's pretty good.
[*] The 95% upper and lower bounds of the uncertainties aren't quite symmetric about the monthly value, which is a pain, so for simplicity I averaged the two bounds to get a monthly uncertainty. The error in doing so, which should be very small, is left (as they say) as an exercise for the reader.
[**] Or rather, this is the actual temperature of the Met Office's model of the world, which is not the temperature of the real world. The model is not reality but an an approximation of reality, and it matters more how it compares to itself (to past temperatures, etc.) than how exactly it simulates reality (as long as the simulation is "good"). Often journalists add the yearly anomaly to 14 °C and write "last year's temperature was 14.49 °C -- and even the Met Office did that in their press release -- but that's not really true and I wish they'd stop it (but understand why it's done). It's the anomaly that matters, and that can be measured, not the "real temperature of the world."
The definition of "good" in the above paragraph is left as another exercise for the reader.