My initial thoughts on the BRO cards (which may well change after actually playing with them!)

Definitely in

Recruitment Officer: Great card, and looks like the second or third-best 2/1 for W in this pool. I already run Militia Bugler and don't mind doubling down on the cheap creature theme.

Obstinate Baloth: Good for the Green decks in the aggressive environment of Peasant cube. I like this over Fierce Witchstalker.

Giant Cindermaw: Simple cards that improves what had been a pretty lackluster Red 3-drop section.

Zephyr Sentinel: Very pushed 2-drop. I don't mind the incidental Soldier text, which will sometimes do things in UW.

Worth trying

Combat Thresher: One of the many 3 mv White cantripping creatures out there. This one has the upsides of also being a ramp payoff and working well with counters. Definitely playable but I'm not sure how many cantrippers I want.

Lay Down Arms: A pretty good removal spell, and I do run some nonbasics with basic land types.

Audacity: A pushed card and a reasonable way to support Green aggro.

Gruesome Realization: I'm not sure if I want more -1/-1 effects in the cube, but I do like the card.

Vague Interest

Skyfisher Spider: I like this card a lot, but it probably doesn't edge out Binding the Old Gods, and I don't think I want both my Golgari cards to be removal spells.

Blanchwood Prowler: I want self-mill in Green and this is a reasonable way to get it. Maybe.

Horned Stoneseeker: Good card, but I'm a bit chary about introducing a new, otherwise-unsupported token type just for it. I think Powerstones are a bit too needy in deckbuilding.

Overwhelming Remorse: If I ever feel like varying up the Black removal suite, this is definitely viable.

Go for the Throat: Ditto.

The colorless artifacts in the set were a big disappointment. I was hoping this set would bolster my weak colorless section, but I don't see anything playable.