I'm probably in the minority, and maybe it's because of my training as a classic Genesis fan, but I always preferred the more serious side of Phil Collins. This is the side that brought us "In The Air Tonight," the cynical "I Don't Care Anymore" and "Tonight, Tonight, Tonight," the addiction song from Genesis' Invisible Touch.
Yet Collins found success with the happier pop and love ballad side of his songwriting (think "Invisible Touch," "Sussudio" and, later, the soundtrack to Tarzan), which is what propelled his 1985 effort No Jacket Required to the top of the charts. Coming four years after that and one year after Invisible Touch, his new effort sought to redact that sunny persona with a more serious, contemplative Phil.
The title alone gives this away, as does the ballad heavy nature of the album and much of the lyrical content. Songs about homelessness, apartheid, fatherhood and gang violence accompany space with slow, heartfelt love songs; there is little here that approaches the lightweight sentiment of previous albums, almost as if Collins was trying to leave that behind and asking fans and critics to take him seriously, something they had not done since his early days in Genesis.
This makes ...But Seriously a moody album, heavy on the slow songs and not terribly balanced, but it is worthwhile for its effort to say something deeper and broaden Phil's sound. By now, he was able to fully integrate the horns and his love of R&B into his sound, so rather than sounding grafted on, they enhance the songs. Case in point is the opening "Hang In Long Enough," a pretty decent late ‘80s pop song with actual drumming (!). "Saturday Night And Sunday Morning" is another winner, a short instrumental that showcases a little bit of jazz chops left over from Collins' days with Brand X. Note: much of the album uses real drums and keyboards instead of dated synths and drum machines, so this at least sounds a little better than Phil's other three albums or 
Invisible Touch.
Would that the whole album was inspired like that, or at least didn't fall back on the same songwriting sounds and cliches that Collins had used up to this point. "That's Just the Way It Is" offers almost nothing musically, although the simple lyrics offer a regret-filled look at a life of violence: "It's been your life for as long as you can rememebr / But you cannot fight no more / You must want to look your son in the eyes / When he asks you what you did it for."
The upbeat songs here fall prey to the sort of cheesy ‘80s synth and horn filler that clogged up No Jacket Required, such as "Heat On The Street," "Find A Way To My Heart" and "Something Happened On The Way To Heaven," while "Do You Remember," "All Of My Life" and "Father And Son" are nearly interchangable ballads.
The center of the album is the most interesting. "Colours" is nine minutes of guilt, a three-part about apartheid with some good lines ("You can take your horse down to the water / Hold a gun at his head / And make him drink") and simple anti-racism affirmations ("These people each have a name...What makes you so high and mighty?"). The song starts as a slow ballad, breaks into a pseudo-African drum duet and then ends as a standard Collins pop song. It's a rarity that his solo work shows this sort of ambition; it wouldn't have sounded out of place on Invisible Touch.
Both of the album's major hits are back-to-back, starting with the Eric Clapton guest spot on the otherwise-moribund "I Wish It Would Rain Down" and the anti-homeless PSA "Another Day In Paradise," which addresses those feelings of guilt one gets when they walk by a homeless person on the street instead of help out. It's a bit heavy handed, but sometimes simple reminders to be grateful for what we have are the most effective. That doesn't necessarily make for a song you want to listen to again and again, but it does its job.
Lyrically, ...But Seriously is the best album of Phil Collins' career, but it suffers from a lack of musical creativity and too many slow songs to make it a classic, even if it was his best album since Face Value.