Fiege & Whedon have both commented on the cut of GotG that they have seen and both agreed that the only fault they see is that there wasn't more Gunn in the movie. Meaning they loved it and wouldn't mind an extra scene or two tweaked with a little more James Gunn humor/style
Having said that, we have all known that GotG was going to be their biggest gamble to date, being in space and with a relatively unknown crew and no direct connection to The Avengers or cameo's by anyone in the previous movies (outside of Thanos). But I can guarantee you that the budget was probably less than $175M (~$150ish maybe) and that it will only need to make $400M WW to be considered a successful gamble. I think on the Marvel studios name alone, it will pull that, and assuming word of mouth is any good, it will pull at least $500M WW, which is really good for a new IP in the MCU stable.
If this movie succeeds, then that paves the way for quirkier heroes like Ant-man and fantastical experiences like Dr. Strange. and what it really paves the way for is the balls to the wall GotG sequel that will follow in 2017/18 with Mantis, Warlock, Dick Rider/Nova and who knows what other space/celestial characters.