Looks preety good to me.
The pictures never show the port side of the boat but if it is like the starboard it looks to be in good shape. It definetely needs a bottom job;to strip, repair and paint. I would check the thru the hulls and if it still had the OM gate valves replace them all with ball type. Check the rudder for integrity and any play. Check the keel bolts. Check the cabin top and deck for any soft spots. After a sound hull the most important things are the sails, how many and in what condition? Check the electrical systems and plumbing. See if it comes with an outboard motor. Make a list of the things that you would need to repair and add (outboard, batteries, bottom job, fuel hoses, etc.) and if you do not go over the average selling price for a similar H25 it may be worth considering. Hopes this gives you a start.