Went there, a good 8 or 9 years, did the Land's End thing (well, you've got to really, haven't you?). If the BLue Reef at Newquay is anything like the one at Southsea, then it's decent enough, but not what you call huge - it used to be a Sea Life, but I guess it was too small for them.
Falmouth is a lovely little town, and there is a truly amazing Fish & Chips restaurant (The Harbour Lights), best I've ever had. Would highly recommend it.