Is this an excellent bet?

do not mess with overs/unders in tennis is my advice

I wouldn't call it an 'excellent' bet as it's just a guess at the end of the day. But as I and most see it as a 50/50 match that will be decided 'on the day' it's probably a 50/50 shot as barring anything ridiculous in set 1, set 2 is probably around 50/50. So you may have some value at 2.25 I suppose.

And going along with that they've played 12 best of three set matches, 6 have been three sets (and the first one which was 2-0 to fed was when murray was 18 and fed a 1.05 shot so that was never likely to be 3 sets I suppose)...

Not too many matches have gone 3 sets this week despite it being a fastish court...

I would actually call it a very poor bet.  The fast conditions usually concedes the winner quickly, which is why there hasn't been many 3 setters.  When the courts are slower they tend to be much more of a war of attrition, that tends to lead to 3 setters. 

I would not take the bet, the rationale behind it is pretty weak.

I would price it a big higher, so it's not good for me, not even mention excellence

Ok thanks lads.