It's a slow-building track, which seems to be constantly working up to the Grand Statement about Their Career to that Point one expects, but Taupin undermines this by instead providing a backward-looking rumination on his childhood and his first songwriting efforts, culminating in this verse:
But that's okay
There's treasure children always seek to find
And just like us
You must have had
A once upon a time
...and if there's supposed to be some sort of summation or observation about where they stood in 1969, on the cusp of stardom, I'll be darned if I can see it.
Elton seems to be striving for a "Hey Jude" approach, with each verse accompanied by instrumentation that's similar in nature to their "Lucy in the Sky" cover, and eventually punctuated by chorus "whoa-oh-ohs" following directly after the verses are done. Then, in what surely seems to be a move to get lighters and hands swaying to the concert audiences to come, the chorus singers take over as Olsson's staccato drum fills and Johnstone's guitar/Elton's piano riffs play, Elton sings a line over and over again in a falsetto voice (which defies my best efforts to make out exactly what he's saying- sounds like "love to love again" or something like that), all building to...not much, really. The song plods on to its extanded fade conclusion, and Captain Fantastic is done. The lyrics are vague, the message is therefore muddled, and the music builds up to a cathartic moment that never really comes.
It's a lovely melody, but I don't think it achieves what it sets out to do. Others, I'm sure, will disagree.