As someone pointed out on another thread, The First Day isn't a Sylvian solo project so of course is different from his solo material (although all DS solo albums do differ quite a lot from each other too).
Personally, I don't understand the apparent hostility to the album - I certainly wouldn't rate The First Day as my favourite, but it does have 2 (and the recent addition of a 3rd) tracks which have permanent places on my all-time best DS list.
Firepower has absolutely no peer among Fripp/Sylvian collaborations - brilliant Frippwork, lovely rhythms and particularly the last 5 minutes - an incredible groove and stunning guitar solo. And as for sheer dirty power Brightness Falls can't be beaten - and the bonus of that delightful final 2 minutes of backwards instrumentation, Fripp's subdued guitar squawks and Frippertronics and Sylvian's quoted vocal phrases...magic.
Then there's Darshan which just doesn't let up...the longer it goes the higher it climbs and as someone else mentioned could well be extended out to 45 minutes....
Apart from the disaster of Jean The Birdman, the rest of the album also has plenty of guts and/or groove.
To me The First Day sounds like Sylvian at his most relaxed musically - with Fripp's shrieking guitar madness and the band's tight rhythms, it all sounds like they're just letting off steam and having a good ballsy time.