A far as I'm concerned, all their albums from that one through Stormwatch were perfectly brilliant. The later ones I don't like as much, and the earlier ones were too "blues". I still need to buy Thick as a Brick Pt. 2, though.
I find some of their later albums quite good, lie Catfish rising and Crest of a knave.
Thick as a brick Pt.2 ... I really don't mind if I sit this one out