It's easy to find people on the interwebz opining about how taking the trip to Australia makes things harder on a baseball team. And there may be certain disadvantages, although I think these are overblown. For the record, I have flown across oceans something like 16 times in my life (I'm not sure about the exact count) and while jet lag can be an issue, I think that for people who are in reasonable shape and enjoyed the comforts of a charter flight, it is vastly overblown. Despite flying coach, only once was I feeling any affects that might have been jet lag a week later, and in that case, I also moved the day after returning to the USA. I know other people that have more trouble with jet lag, but the only people I've known that were having problems that much later were in generally bad shape.
More concerning is the playing of spring training games between meaningful games. Can players turn it off and turn it back on? But players frequently do this anyway, when rehabbing from injuries after spending time on the DL. And while the idea of a "hangover" after these trips has been expounded upon, every trip to Japan has produced a playoff team, and the 2000 Mets, without the benefit of a full week off between games, went 15-9 in April and went to the World Series. Not only did they not have a full week off (as will the Dodgers, the Diamondbacks will have eight calendar days) but their game played on Thursday in Japan went 11 innings.
I actually think that, long term, opening the season abroad can be a benefit to the teams participating, particularly if these teams do not have a lot of depth. Most teams are playing 162 games between March 31st and September 28th. The D-backs will play only 160 games over that same stretch. Considering the exhaustion that the team faced during the summer last season, those extra days off could prove invaluable. Last season, the D-backs had 8 days off June-August, apart from the All Star Break. This year, they have 10. With the lack of depth for players like Parra, Goldy, and Montero, having those two extra days off could prove important down the stretch, as that means all of the above players (assuming they are healthy) will be able to play more games.
Never in the past has MLB taken two teams that were possible contenders across an ocean to play the season opener. Of the previous eight teams, only three had finished .500 or above the year before. Of the eight teams, three finished with a better record than the year before, and one the same record, but none experienced an extreme drop-off (overall, teams have finished 28 games better in seasons when they opened in Japan than they have the year before. Admittedly, removing the 2012 A's and Mariners teams finish on average exactly the same as the year before, but the only extremes are extreme improvements, with the 20 game improvement by the A's, 8 game improvement by the Mariners, and 7 game improvement by the Devil Rays in 2004 being the three largest changes.) No team has ever opened in Japan (the only previous trans-ocean opening site) and finished more than 3 games worse than the year before.
In conclusion, while there are certain irritating things about opening the season abroad (and the Dodgers commented on all of them), it seems to me to be more of a competitive advantage over the course of a 162 game season than a disadvantage.