Marrita,
Kind of a broad question, but I'll tell you what I know. I own a 1989 255XL with a 7.4 Mercruiser/Bravo outdrive. This was our first boat and normally weekend with 4 people on Lake Erie. The boat has a solid fiberglass hull-no core. Our boat holds 79 gallons gas, not sure of fresh water-guessing 15 gallons but we've never run out over a long weekend, and probably 10 gallon??? waste. As a first boat I have had NO complaints. She is always smooth and predictable, even when Lake Erie picks up. Ours is not a fast boat, I normally cruise about 3000 rpm/23-25mph. Of course it will go faster but I'm never in that big of a hurry.
As with any boat please have it surveyed by a competant individual. This boat is almost 20 years old, many don't last that long.
If there is any specific questions I can answer please don't hesitate to ask.
Chris