True, most people don't talk like that, but it is grammatically / punctuation correct. In fact, I tend to write like that. If you've read my TIMELINES story, you'll see a lot of compound / complex / compound-complex sentence structure.
The worst thing about dialogue is when the author attempts to convey a thick accent. Too often it ends up with whole sentences made up of words spelled "wrong" or clipped with apostrophes all over the place. It's supposed to "read like it sounds", but I'm reminded of the screen in the movie BRAVE where the big guy talks, and everyone looks at each other like "WFT did he just say?" Just toss in a few simple words with the accent and leave the rest spelled correctly, please. We'll get the gist that Scotty has a broage accent.
Oh, and I have the same issue with foreign / alien character names. If they're too weird, it makes my brain stumble every time I see it. I have a character in a story named Sarisha Sahani. She is of Indian decent (Hindu, not Native American), so she has a unique name, but it's not unpronounceable. I cringe when I see characters named something like Ps'K'houewe'T'sca'woo. Seriously, why do that to your readers?