Over 15.5 3's made by both teams combined at -140 is that rarity: a prop bet with value.
Consider:
In GS's last 5 games:
12-31 Game 1 against Utah
14-30 Game 6 against Dallas
16-35 Game 5 against Dallas
12-31 Game 4 against Dallas
14-30 Game 3 against Dallas
With Utah keeping the pace and getting some wide open looks in Game 1, a team that was not a 3-happy team in the regular season, turned into a capable outside shooting team in Game 1 against GS. Utah was 8-23 with Okur, Giricek and Williams combining to go 8-21.
Granted, the major underlying assumption here is that GS will attempt at least 30 3's and shoot 33%, leaving 6 3's for Utah.
I think the pace will allow a few 3's for Utah and GS will get theirs. Usually not one to play NBA playoff props, but I just dropped 2.5 units on this one.