Hm, I wasn't going to do this considering i've discussed Iris on both my blog and another thread, but sure, this will take more explaining than what's probably necessary. When it comes to my take on the matter, I really have a lot to say.
For starters, this was something someone said in a "worst/least favorite champion" topic on the Marriland forums a while back in late 2013 I think. Now, not that i'm trying to say Iris is so much better than Cynthia or Steven or what not (because then i'd get hate comments for days), but honestly, any Champion can be easy or hard based on your coverage, considering how many options you'll have when you're at the end of your adventure. While one person might waltz through Iris, the next might get slammed by that Dragon Dance Haxorus. Same with Diantha, there are people who breeze through her while others get their butts handed to them by Mega Gardevoir. Heck, even Steven and Cynthia could be a joke with the right Pokémon, but i'm getting too ahead of myself.
For that matter, even older players (like myself) might not mind something being easy. I do know that the creators mentioned that they wanted to make the games easier because they know our lives are getting busier, and I know some people would prefer not having to grind much.
But enough talking about that - now to get on topic and discuss why I actually like Iris as Champion myself. And i'm not just gonna rave about her battle music and that awesome rainbow beam space battlefield (although those certainly throw quite a bit of spice onto the battle for me).
To begin, I think she's creative, and not a character a typical player would probably expect as Champion. I say that because she's likely around the age of the Unova protagonists themselves, and to have a female character of that age rocking a team of dragon and monster Pokémon in a dynamic space battlefield? Yes, please.
And it certainly helps that she uses many of my favorite Pokémon, including my favorite of all time (Lapras), as well as Aggron, Hydreigon and Haxorus. That may be one reason why I always look forward to battling her and what has made B2/W2 my favorites, and why I have made it a habit of replaying them on Challenge Mode (well, doing challenges on them), because she uses so many Pokémon that I really like.
That's not to say I think she's perfect, though. It would've been great if they had gave her some action in Opelucid City after Team Plasma freezes it, or in the Plasma Frigate/Giant Chasm near the climax of the main story. At the same time, I have wondered what would make for her to have a better team out of BW2's Pokédex if they had dropped the Dragon-type theme from her. (For starters, being more than one level above the Elite Four before her would've been nice…)
In short, if they had gave her more screen-time in the story, or a more balanced team, and kept that music and battlefield, she would definitely be my favorite Champion of all of them. I have a feeling people may have liked her more if Challenge Mode was available from the beginning of the game.
So yeah, that's my take on the matter.