"A Momentary Lapse of Reason" came out after Roger Waters (the main songwriter up to this point) left the band in pursuit of a solo carreer. Pink Floyd fans are generally a little disgusted by the heavy 80s sound of this album. Consequently, this gets a lot of bad reviews. I'm not going to throw in that catch-phrase used way too often ("a highly underrated gem!"). What I will say is that fans of Pink Floyd often dislike this album, so people who've never listened to this avoid it. This is what makes this "underrated." Although David Gilmour (guitarist and now the default songwriter) does play excellently on many tracks, the songwriting is not up to the caliber a Pink Floyd fan is generally familiar with. Almost all their albums up to this point sound so unlike other albums of their time period, that people say the music is timeless (they don't sound dated in other words). This album sounds dated major time. That does not, however, mean that this music is bad. On the contrary, there are some really great songs; albeit not as great as music from previous albums, but really quite good. There are some moments of almost ambience, like "Signs of life" which is very minimalistic, but most of this stuff has heavy drumbeat and maybe a little too much synthesizer work(weird to say that about a Pink Floyd album, but it's true). Like I already mentioned, most of the tracks are very 80s, but some tracks, like "On the Turning Away" sound distinctly like it belongs on THE WALL. "Sorrow" might be the best song on the album, but not by much. Most of these songs have good guitar solos, and the one on "Sorrow" is the longest, but it doesn't sound anything like the beautiful guitar solo on "Comfortably Numb."
If you want a flavor of this album, listen to the songs "Run Like Hell" and "Young Lust" from THE WALL. That'll give you a pretty good idea of what to expect.