It's an eminently respectable kit - in some ways a better scale model than the Heller Soleil Royal. What problems it has stem mainly from its age. It was originally released (according to Thomas Graham's Remembering Revell Model Kits, the bible on the subject) in 1959. At that time it represented the state of the art. It was the biggest, grandest product the plastic kit industry had to offer - and, with a retail price of $10.00, the most expensive.
Some of its features stand up quite well even by today's standards. The crew figures are wonderful, and the figurehead, to my eye at least, is a finer specimen of feminine anatomy than the one on the real ship. The basic shapes of the ship are quite accurate. (That's where it scores over the Soleil Royal.) This kit can provide the basis for an excellent scale model of an beautiful, important ship.
It does have its problems, most of them related to the company's efforts to simplify it - and, to some extent, to technological problems that hadn't been worked out in 1959. The maindeck is molded in three pieces - fore, midships, and aft - that create a nearly insoluble joint-filling problem. Some of the detail parts are a little on the crude side; the cargo winches, for example, are kind of blobby, and the paneling on the sides of the deckhouses is represented by raised outlines. The real ship is composite-built, with wood planking on iron frames. Her bulwarks - the sides of the hull above the level of the maindeck - are sheet iron, supported on the inside by sloping iron stanchions. Revell represented those stanchions with integrally-molded triangular gussets. It wouldn't be hard to shave the gussets off and replace them with more authentic-looking stanchions; on the other hand, the problem isn't too conspicuous on the finished model.
The carvings at the bow and stern are represented by water-slide decals. They're nice decals, but if you're buying an old kit you'll want to be careful with them. Sometimes decals hold up well over the years; sometimes they don't.
The kit's biggest deviations from scale accuracy relate, as usual, to the rigging. It comes with plastic-coated thread "shrouds and ratlines," which are best consigned to the trash - along with the hideous vac-formed plastic "sails," if it has them. (The original, 1959 issue of the kit didn't.) A more serious problem concerns the molded plastic "deadeyes and lanyards." They look pretty phony; they're good candidates for replacement with aftermarket parts from Bluejacket or Model Expo. The lower ones also are far too thick, and that inaccuracy has had an odd chain-reaction-type effect. The Cutty Sark's lower deadeyes are mounted inside her bulwarks, on top of the pinrails. The pinrails in way of the deadeyes are a little wider than the pinrails elsewhere along the length of the ship - but nowhere near as wide as the ones in the Revell kit have to be in order to accommodate those overly-fat deadeyes. The result is that the pinrails look grossly out of scale. They also have plastic belaying pins cast integrally with them. Plastic belaying pins, even if they haven't been busted off before you open the box, are an invitation to disaster. If I were building that model, one of the biggest improvements I'd make (which actually wouldn't be too difficult) would be to replace the pinrails, deadeyes, and belaying pins.
Some excellent sources of information about this ship are conveniently available. The very best, in my opinion, is the set of plans drawn by George M. Campbell. They're among the most fascinating ship drawings I've ever seen - three sheets crammed with every detail one could possibly want to know about. (And a few one might not want to know about. In the middle of the stern is a carving representing the family arms of the ship's owner, "Jock" Willis. Around the edge of the carving is the family motto: "Where There's a Willis Away." Fortunately it's far too small to be legible on 1/96 scale.) The plans are available for an extremely reasonable price (about $15, I think) through the ship's website. (The address escapes me at the moment, but a google search would find it in a few seconds. It also contains quite a few good photos of the ship.) Several web acquaintences have ordered those plans lately; they report fast, courteous mail service.
Mr. Campbell also published a fine book, China Tea Clippers. It's full of nice drawings, and does a good job of putting the ship in her historical context.
If you want to read up on the ship herself, the best book is The Log of the Cutty Sark, by Basil Lubbock. I believe it's still in print, but pretty expensive; it should be possible to find used copies on the web, though.
C. Nepean Longridge, one of the best ship modelers ever, built a fine model of the Cutty Sark back in the 1930s on 1/48 scale and published a book about it: The Cutty Sark: The Ship and the Model. The book is a classic of the field - though obviously dated in terms of materials and techniques.
Hope that helps a little. Good luck.