Sorry Suzanne78 but i've never agreed with statements like this one.
I think it's always been a fanboy fear of wanting the GA to accept the nerd **** that we're into. Fox/Rothman had the same ridiculous worry when it came to Galactus in the second FF film. So they changed him into a space storm of some kind, or hid him in it at least.
I've said this in past discussions on this very topic and I'll always use this example again and again. If people were ok with(and loved)a giant marshmallow monster in Ghostbusters there should be no worry about them accepting this or that. Star Wars alone proves that with all the crazy looking aliens that appeared. Fans with this worry tend to forget that this is by far Not the first time the GA have seen wacky characters that don't exist in real life and they've accepted it numerous times in the past. Groot and Rocket won't be an issue at all. The only people that will find it stupid are the ones that found films like Star Wars stupid. People that only seem to like straight forward dramas and whatnot.
Let's also not forget that people know this is a comic book film due to the fact that it has "from the makers of IM, Thor, etc..." all over it. They will be ready for some wacky fiction due to it being based on a comic book. The success of this film will all rely on if there is good word of mouth/good reviews, and Marvel's name of course.