I brought my family to see it in Denver the other night... SOME SPOILERS!
It cost as much per person as a single day ticket to a WDW theme park, with no discount for children, of course. The entire family was very excited to see the show, and we made a whole evening of it, dressing up (no one ever does that in Denver) and going out to dinner at a fancy restaurant first.
Herewith, my impressions:
-The male and female leads (Eric and Ariel) were outstanding. Both fit the roles well and had a strong stage presence and excellent voices. They carried the performance.
-The sets left a little (a lot?) to be desired. Other than the boat featured prominently in the first number (Fathoms Below), the sets did little to transport my imagination to the world of the story. There were a couple of mechanical devices that look like giant wine bottle openers (the kind of corkscrews with handles on both sides that one squeezes to extract the cork) that kept reappearing in multiple scenes--under water, on land, and in the palace. They were distracting and lacked the organic form that might have helped them blend into the scenery better. This is an area in which significant improvements could be made, and I wonder if there are plans for more once the show reaches Broadway.
-Similar to the sets, the costumes disappointed me. Perhaps this is because I kept comparing them to the costumes from the stage production of The Lion King, which probably isn't fair, given how ground-breaking and amazing those costumes were. Nevertheless, I thought the costumes were too heavy on sparkle, an odd degree of androgyny, and accordion-like folding paper devices (Ursula's tentacles and Under the Sea's blowfish, for example). I also didn't find the "heelies" the actors used to mimick gliding through water convincing as a representation of swimming, though I admittedly cannot conceive of an alternative.
-The supporting cast was very good, for the most part. Sebastian lacked timing or volume or something in singing Under the Sea, so the number didn't have the show-stopping impact it claimed in the movie. Kiss the Girl, on the other hand turned out nicely. The actress playing Ursula has a fine voice, but seemed less imposing and threatening in singing Poor, Unfortunate Souls than what the film left me to expect.
-On the other hand, Ursula, Ariel's sisters, and Scuttle all have bright, fun, catchy new numbers added to the "soundtrack" just for the show. If I remember, the songs are "I Want the Good Times Back," "She's in Love," and "Positoovity," respectively.
-With an understanding that some of the effects seen in the climax of the film would be difficult or impossible to replicate on stage, I would still say that the end of the live production was insufficiently dramatic and a bit logically implausible, even granting that it all takes place in a fairy tale world.
In all, we enjoyed the show a great deal, but concluded that The Lion King remains the regal standard by which all Disney stage productions will continue to be judged. Also, my wife admonished me for being too critical, so take it all with a grain of salt.