I really liked the Dreamcast version, although at the same time I found the random battles really annoying. However, with Legends I heard they lowered the ratio of random battles and the ratio is bearable now (I didn't play it yet).
The music is very nice and has an upbeat feel to it.
And yes, the upbeat atmosphere of Skies of Arcadia Legends is a great change to occur. Not enough RPGs nowadays have the adventerous and lighthearted atmosphere that Skies had, to the point that Skies of Arcadia is actually a rare breed

.
The battle system itself is very well designed IMO, with a good balance with the spirit meter.
I never beat the Dreamcast version though as my file got deleted, and then I heard about Legends.
The airship battles are nice, although I found them a bit on the slow side, not sure if they sped up the pace in Legends.