It's pretty rare that restaurants improve. Usually, bad ones close and good ones either stay the same or get worse. Spiga has gotten better.
Some of my family's favorite dishes are the antipasto arrosto (various roasted seafood and stuffed vegetables), the filet mignon (the crispy leeks and mashed potatoes are soooo good), the zucca salad, the pasta de bosco, and the chicken francese.
Not everything is good, though...the scarpiello and the saporito were both disappointing -- too dry, and simply not as good as similar dishes at other restaurants.
Also...they have a dinner special that isn't on the menu and that's probably the best deal in Scarsdale. You can get chicken parmigiana or eggplant parmigiana for FIVE, and it comes with pasta, soup, salad, bread, and dessert -- again, for FIVE, all for 40 bucks.