Yeah, Psygnosis had some seriously difficult games.  Blood Money was frustrating.  So was "The Killing Game Show."  I never made it past about 4 or 5 levels, when apparently there were a good 100 or so.
Pinball Dreams I never found frustrating, though.  A really great pinball experience.  (Though I went through some SERIOUS frustrating times getting it to work right on my A1200!)