Desert Dog lays it out as he sees it:
Decision: 20% chance of happening, GSP win's this outcome 95 % of the time. (Very unlikely Serra can control GSP for the majority of this fight due to reach and strength. GSP may use same plan he used with Koscheck and others.)
TKO: 50 % chance of happening, GSP win's this outcome 70% of the time. (GSP has the reach and wider arsenal - kicks especially dangerous here. Serra has power and good enough chin to get inside and of course he did it before.)
Submission: 30% chance of happening, GSP win's this outcome 65% of the time. (Both are very skilled with submissions. Serra has experience edge, but GSP has strength edge and will be more likely to be in the dominant position.)
TKO: 50 % chance of happening, GSP win's this outcome 70% of the time. (GSP has the reach and wider arsenal - kicks especially dangerous here. Serra has power and good enough chin to get inside and of course he did it before.)
Submission: 30% chance of happening, GSP win's this outcome 65% of the time. (Both are very skilled with submissions. Serra has experience edge, but GSP has strength edge and will be more likely to be in the dominant position.)
Using various forms of fuzzy math GSP should win this fight about 72.5% of the time so odds of -270 or better would have value. The best odds offered on GSP are -450 at Bodog.
On the other side of the coin Serra should win 27.5 % of the time and odds of +270 or better would have value. The best odds offered for Serra are +375 at Bookmaker.
Serra doesn't get credit for being very hard to finish and having excellent defense in every aspect of the game. With the exception of Shonie Carter's spinning backfist late in the third round, Serra's never been finished. I say GSP by decision.