I’ve had a pair of the Zeros with Ti axles on my road bike now for three months and I really like them. I would second everything fhendry1 said and would add that they are actually easier to clip into once you learn to apply more pressure; indeed they are not unlike clipping into Shimano SPDs in that you step down onto them, rather than forwards into them as you do with Look/Shimano road pedals.
I find the cleats are as easy to walk in as other designs and yes getting dirt, stones, mud etc in the cleats will prevent you from clipping in but I’ve not had that happen to me yet.
The thing I really like about them is the range of adjustment they offer. Not only is it really easy to adjust both the amount of rotational play and the angle of your heel (done by simple adjusting two grub screws on the cleat) they are the only pedal to offer lateral adjustment.
I have very broad feet so short of trying to obtain some Dura Ace pedals with extra wide axles (which you can buy but are hard to source), these are the only pedals I’ve had that enable me to get my feet far enough out so my instep doesn’t rub on the crank.
They are light and also robust so far, though they are only a few months old.
Hope that helps.