I will give Kobold's credit for being sly; they picked two the biggest classes in 5e that WotC hasn't covered yet in their playtest so that we cannot (would not?) compare them. I imagine if the first classes BF released were rogue and cleric, we'd have just spent the majority of the discussion comparing them to the 1D&D versions and debating which company was actually fixing the problems.
That said, I see once again Kobold (like WotC) have been copying Paizo's homework in that that there are universal spell lists that every class will share. They also moved subclass features to 3rd and 7th level, (the fighters were that prior, but the wizard was 2nd and 6th) which makes me think that they too will have subclass features align across all classes (though with only 2 classes and not even all 20 levels, that is a bit of speculation). Regardless, I wager that some conversion of prior subclasses will be necessary for BF as well, which again puts their level of "backwards compatible" about on part with One.
More interesting is that rituals are no longer regular spells you can choose to free cast, but only castable as rituals. It somewhat makes sense to take spells that are purely utility and typically cast outside of combat and silo them away from spell slots. It's also worth noting that Mage Armor is a +3 to AC rather than set your AC to 13, which may have some interesting implications with things like Unarmed Defense.
I'm also growing less enchanted with terminology changes. Talents, Circles, Rings, and Stunts are just Feats, Spell Lists, Spell Levels, and Maneuvers with legally distinct names. I'm sure if I played it, I'm sure the new names would stick, but for the moment, they throw off my comprehension of the rules. That's a nitpick, but if the goal is compatibility, terminology changes are a bad way to do it.
Overall, my opinion of BF hasn't changed; there isn't anything yet that has made me thing this isn't basically Two D&D. It's not really offering anything that WotC isn't offering, just doing so in a different way. It will be interesting to see when they handle a class WotC already covered (like Druid) to see how the two directly compare how they intend to solve the same problem points.