Early days.
I didn't love Karen Hauer (before she was Clifton) when we first saw her (though didn't hate her by any stretch obvs), but I like her much more now and think she's even quite funny in a nutty kind of way. She doesn't take herself seriously (which I quite admire in a person) and I think, given how she's been dressed/made up on the show at times, a good sport. It probably wasn't until she was with Dave that she finally grew on me.
In contrast, the moment we saw James Jordan I didn't warm to his personality or care much for watching him dance mainly, and that barely changed throughout his time on the show. While I had no problems with some of what he said, I just found him up himself, lacking in humour (or be it didn't gel with his brand of so called banter) and prob pref all the new male pros that came after him, easily by far.
So, sometimes you need to wait it out, even for some seasons.
I don't think it matters they look young, as of course anything highly physical profession, sport or dance, is something that lots/most are at their prime in when they're in their 20s (for the career and titles goals). Obv the older I get the younger someone looks (like Chloe & AJ), even though actually they're not getting younger really, I'm just getting older.
The new Pros seem fine, imo, and we have to remember that once they get into the grind of Strictly they open up more, relax and can sometimes seem totally different to our inital reactions,