My first thoughts on A Single Man was how tough it would be to review. On one hand, this is the first album without any Bernie Taupin contributions. On the other hand, its stripped-down sound is appealing after the sometimes pompous grandeur of Blue Moves. I feel like Steve Zissou today, so let's go exploring, shall we?
The opening track "Shine On A Through" is a vastly
reworked version of the track that appeared on the Thom Bell
Sessions. Instead of a Philly soul/disco number, you've got a
standard Elton ballad. Nothing too fancy, but not a song to be
skipped over either. "Return To Paradise" foreshadows "Cold As
Christmas" but chooses to employ a Caribbean sound instead., while
"I Don't Care" is the rave up rocker, at least in terms of the rest
of 
A Single Man. However, I do appreciate letting John sit
back and play with very little accompaniment. If there is one thing
A Single Man does well, it is show off John's piano
proficiency.
"Big Dipper' is a honky tonk number that for the first time featured a lyric that embraced John's homosexuality. It doesn't take a rocket scientist to figures out what "Big Dipper" symbolizes. Interesting note of trivia -- the ending refrain features the entire Watford football team that John owned at the time.
"It Ain't Gonna Be Easy" tries its hand at a blues/rock blend but goes on for about 4 minutes too long. The song does spotlight John's new vocal styling, which more fully utilized his range. Things get back to the comfort zone with "Part Time Lover," the epitome of an average Elton John pop song. It's catchy enough to be a single, but is utterly forgettable afterwards. Davey Johnstone plays guitar on the track, one of the few instances of continuity with his old lineup from previous albums.
The two standout tracks occur within the last three songs. "Madness" and "Song For Guy" are underrated classics. The former boils over with intensity, totally belying its disco beat. John's vocals are the key here, totally capturing the feel and mood of the lyrics. He snarls, rages, and even throws in some of that classic falsetto. "Song For Guy" is a rare instrumental, written as an ode to a departed member of John's Rocket Records staff. Built around a recurring theme, Elton adds various flourishes that help establish this feeling of a dream.
The version of A Single Man that I bought contains a bevy of bonus tracks that have become part of the album to me, with stronger hooks and performances. "Ego" in particular is a disjointed, jarring affair that does not sound like an Elton John single, but it was just that. With a hint of madness in that voice, John starts to freak you out towards the end. "Flinstone Boy" is another attempt at country, but it works quite well, mainly because Elton doesn't countrify his voice and lets the music speak. Finally, "Strangers" has always caught my ear for reasons I can't define, though the simple delivery and affecting lyrics/vocals are a few reasons.
As an Elton John fan, I see this as one of his most underrated albums, but as a critic it's only decent and not spectacular.