I'd probably say they distort the view a little for my taste. Maybe my expectations are low. I have seen a 7,000 gal round pool at PredatoryFins recently with round polycarbonate windows and was surprised how well I could still see the fish, how they were not objectionably distorted.
The 180 is old, crazed, but nice and clear after many, many hours of polishing. I built the stand for the 6' x 24" x 24" 180g. Now I am kind of perplexed at what size aquarium to build with this new acrylic? I could build a much nicer 180g. I could build a 30" tall x 24" wide x 6' tank and it would fit on my stand.... I had a 110g tall tank which was 30" tall and maintenance was a pain in the rear trying to reach the bottom. Or I could build a new stand for 24" (or 30") tall x 30" wide x 6' long tank.
I think I need to get the current 180g up and running then worry about building a new tank.... if I don't I will never have a big tank up and running.