I'm someone who found her DD to be a very difficult baby (didn't sleep through ever til a year old, and then very variable til finally gave in to CC at 18 months or older), reflux, colic, late on lots of physical milestones, difficult feeder, fussy eater, allergies, very clingy etc (but I should point out also the cleverest, most beautiful, funniest girl in the world in my eyes!). I think I would prefer someone like you to take the, "I'm so lucky my DC is..." tactic than either pretend it is as hard for you (and make me think 'how does she seem to be coping so much better with it then, I must be rubbish at this') or moan about little things just to join in.
For example, I once got speaking to a mum with a baby a little younger than mine when DD was about 7 months, and told her DD was waking up a couple of times in the night and very early in the morning most days. She said hers was sleeping through 7-7, and I thought - lucky you, without feeling at all bitter about it or thinking she shouldn't have said that. However, she followed it up with "It's so hard having to wake up at 7 every single day". I really had to bite my tongue not to be rude then (and I'm not a confrontational person). I don't begrudge her having a moan about that (I moan about similar things now DD is 2 and does sleep through), but never to someone getting much less sleep!!
So I guess I'd agree with the majority on here - be honest about your DD, but make sure it is in a grateful way, not smug!
Oh, and one of the best pieces of parenting advice I ever got was to always ad "at the moment" to the end of things you say or even think about your DD, e.g. "she is sleeping through at the moment" or "she is really difficult at the moment". it makes the bad things seem less permanent and makes you less complacent about the good!!