OK, I'm a little late....I was typing this last night but got cut off from the internet. Here's my take on it in a long pointless post....
I thought she was quite funny in DotD. There was one joke that made me think of Irish humour for some reason!

She's not outright hilarious(that's Sparx's job!

), but she's the "subtle, smart" kind of funny, and usually makes me say "ha, good one!".
If you think about it, she is already half anti-hero. Anti-heroes tend to scold the main hero, and Cynder scolded Spyro sometimes in DotD. The main reason I don't want her to become a total anti-hero is because - as CAV said - it happens ALL THE TIME! I'm a huge Final Fantasy fan, but even I can admit that it's annoying the way there is usually a character who is good, and all of a sudden turns into an anti-hero or bad guy in nearly every game. And it's not just Final Fantasy I see it in. Even Avatar, that blockbuster movie, has it. Also, they have spent three games building up SpyroxCynder, and for Cynder to just not really like Spyro all of a sudden would be just weird, if not stupid. Also, hasn't her alignment changed enough already? First she's evil, then she's good, then you can't tell, then she seems bad but is actually good, then she's most definitely good again, but then she's corrupted and now she's good AGAIN!!!! Not to mention that in the GBA version of TEN, we are lead to believe she is brainwashed for the whole thing. Seriously, I'm suprised it hasn't become an inside joke, like Sparx's voice over changes....
Cynder is also one of my favourites, and I can think of flaws in her character, but they make her a more balanced, and therefore, interesting character. I don't think her personality is the problem - it's the fanbase. You've got so many people asking for so many things from one character, that people don't know what to choose. Which is why her personality shouldn't
change, but develop, and yes, there is a difference. If her personality stays basically the same, but develops, then people will like the steady character development, and haters will just get tired of asking her to change to their liking, and move on. If you keep a character consistent, they will have a consistent, larger fanbase. If you keep changing them, then smaller groups of people will like them, but everyone else will be arguing over which personality they would like, which is most likely identical to a favourite charcter of theirs. Different people will like and hate the character with different "versions". You know, it's ironic - people were complaining....no, scratch that.....people ARE complaining about her "personality change" from TEN to DotD, and now they are asking for one?....seriously, let's not start a cycle between each game....I can see it now...."THE CYNDER CYCLE!!!"(In case you don't know, it's a joke relating to "The Sonic Cycle")
Also, I'm sick of having to say and read "ANB Cynder, TEN Cynder and DotD Cynder". Cynder is Cynder to me, the same character with the same personality across all three games. Yes, she was corrupted in ANB, but was still the Cynder fans know and love deep down. I don't want to start seeing "SK Cynder"....
Sorry for that long post that nobody will read, and if anybody does read it, they will probably bash me. I just had to let that out. I could go on all day, but I just punched myself in the face and said "OK, that's enough for now....."!
Hope I don't come across as an example of a "Cyndork", whatever that even means(must make me sound nooby)!

.......
*shot 100 times with a mini-nuke launcher for this post*