I've dined at 300 East several times...2-3 dinners and 1 Sunday brunch. Ambiance is more of a warm and cozy vibe. You feel like you're dining in someone's house! Can get a bit loud depending on where you sit, so I would say this place is most conducive for parties of 1-4 people (maybe 6-8 if you sit upstairs and they put tables together.
For dinner, their French Onion Soup is great. My dad ordered it last time they were in town and the flavor was REALLY good. I'm also a fan of their chicken, which is so juicy and delicious! Definitely enough to take home for leftovers. I've also had the steak here before and it was certainly worth getting! Dinner gets a solid four stars.
For brunch, my love for this place died of disappointment today. Service was so incredibly slow and the waitress never came to check on us during the meal until it was time to clear the plates. My Breakfast Pizza was clearly burned, which was disappointing as I looked at other well-made breakfast pizzas around me with lots of toppings and fluffy crust. Brunch gets a solid two stars. One star because the Mimosa was good and another star because I tasted the other dish on the table and it was pretty decent.
I would recommend this place for dinner and that's it. I would pass on brunch so you don't run the risk of getting a sad-looking, overcooked breakfast pizza like I did.