There are "phases" to Porcupine Tree.
First comes the spacy phase (Sky Moves Sideways, Signify, basically the early years).
Then came the poppier stuff (Lightbulb Sun, Stupid Dream).
Then came the harder prog-metal stuff (In Absentia, Deadwing, Fear of a Blank Planet).
Then came the bad album that the record companies pushed and made them popular (The Incident).
Then came Steve Wilson's solo stuff, which leans more toward the spacier stuff in the beginning and is well worth the listen (Insurgentes, Grace For Drowning)
In my mind though, it's all good.