While necessary at some parts, dowsing made others seem too easy and unfortunately felt unnatural to the Zelda franchise. I vote for this mechanic to not return in the future.
sPOILER: Yes! I hated that part :OWell, now is probably not a good time for me to answer this question, considering I just completed the most grueling portion of the game thus far. That is,
trying to dowse to find the five shards of the Earth Temple key.
That was the most annoying, frustrating portion of a game I've experienced in a really long time. See, the dowsing is really nice... when you're only dealing with one level or floor. When there are different levels of elevation, dowsing is just incredibly inaccurate. Not to mention that it was incredibly difficult to dowse accurately due to the gigantic mountains I couldn't actually see around. Although, I have to admit, if it weren't for dowsing, I would have definitely cracked and started using a walkthrough to attempt to find the shards. It wasn't the dowsing that was frustrating, it was the actual locating and reaching the shards.
I don't use dowsing often, but because it has actually helped me (and prevented me from using a walkthrough like I always do), I'd probably say I love it. It's an interesting new mechanic, but one I think fits Skyward Sword nicely. Many aspects of SS are more technologically advanced, like the Beetle and Fi herself. It's only fitting that Fi, who sounds like an actual robot, could come up with something as techy as dowsing. I won't vote until I finish the game, but as it stands, dowsing is quite convenient and I'll probably be grateful for it later on.