I saw the performance this evening and I think Rannells is a different take on Hedwig that also works, but I'm quite biased that I prefer NPH (though I definitely would prefer JCM first since I've seen the movie several times!)
*possible spoilers below so don't read on if you don't wish to know them*
Since everyone has access to "Sugar Daddy" from the Tony Awards --- some things Andrew did differently on that song in tonight's performance were: no kiss & no eyeglass licking! Just an FYI in case you bought tix in the hopes of getting a kiss or lick from him.

I'm not 100% sure whether NPH did all that in all his shows but I did see him perform Hedwig 9 times and in those 9 instances he did all of that.
Overall I think Andrew will be amazing but I think he rushed a bit on some of the jokes, especially with the folks sitting in the box seats (Andrew made a grindr joke but none of the people in the box laughed so I'm guessing they were all straight and didn't know what it was?) I understand this is only his 3rd performance of this production and it'll take time for him to settle in. His version of Tommy Gnosis though was superb!
He's still a bit nervous too, I think. He said some odd lines like "Put down your $75 cocktail..." (during the wig song before the sing-a-long) and "Yitzhak! You can speak sightreading" (right before Yitzhak sings Love Theme from Hurt Locker.) He didn't do the "sing my angel of music" reference too but that's ok.
I understand his take will be different and that's ok since his version works too! Overall I think he did a great job! For those who saw NPH and AR perform, would be great to hear your opinions as well!