A lot of it is intentional, the safeties are playing really deep to prevent big plays, but it's put a lot of strain on the LBs as Hicks is not good in coverage and Kendricks has been regressing. The benefits have been apparent, with more interceptions coming because the DBs are actually looking at the QB compared to Zimmer's man-heavy schemes which always had the DBs facing the receivers and never being able to make a play on the ball, leading to low interception rates for CBs. And that scheme demanded top tier CBs to be able to function. The downside with Donatell's scheme is that if the QB gets enough time in the pocket or can scramble, the receivers can run to the gaps in coverage and make plays, and also get some big opportunities for YAC (see Rondale Moore yesterday). It's been used to frustrate the high-power offenses that don't want to 'take what the defense gives them', but it's only going to work if the offense keeps scoring 28+ points a game since our defense is usually going to keep the other team in the game.
I'm not sure what you mean by the LBs being the best part, are you including the OLBs? Smith has easily been the best player on the defense, with Hunter looking good not great, and Wonnum looking much better than before and even Jones looked great against the Fins.