An excellent choice
I have owned/sailed a 1974 C&C 25 for the past 5 years. I Have owned 2 other (larger) C&C boats, and a total of 7 sailboats in all. So I have something to compare this boat to.
It's an excellent model. Built strong and simple, but very fast and forgiving. It has the feel of a big boat, not in small part to the 50% ballast to displacement ratio...making it a good stiff sailor (stays upright). Below has a ton of space compared to any other boat in it's class. I take a family of 4 for a week, with no trouble, except maybe if it rains for three days in a row. The outboard is preferred, because you can have a modern 4 stroke engine rather than a 30 year old inboard (yuck). This boat is easy to sail, very strong, and handles all weather and waves without trouble. The shallow draft will get you anywhere. The huge companionway hatch makes the below very open and airy, and easy for entry/exit, especially for kids.
However, here's some things to look for when purchasing:
Deck leaks cause soft spots in the balsa core. Check the decks carefully, especially on the bow and near the chainplates. Most have had the deck repaired already. If it's soft, you'll be able to easily tell. Check the mast step for cracks. Many have been replaced, which is ok. The mast can be lowered on a pin, but this puts alot of undue stress on the step and leads to damage. It's better to use a crane, and easier/quicker too. The original electrical should be ripped out entirely. Replace with a new breaker panel, and LED lights. OR...just buy some flashlights for at night...12volt power isn't really needed these days on a small boat...I use handheld VHF, GPS, iPod, etc. And finally, check the sails...many have original sails. Newer sails will increase speed and look great. A nice feature of this boat is that replacing stuff is easy and cheap because the boat is small. A whole new engine will cost the same as one big repair of an inboard engine. New sails under a grand each (or can use used sails from a similar sized rig). New anchors, lights, cushions, and you've got a great boat...just like mine! So go ahead and buy it, and you'll be a happy sailor!