Malt extract is both a great way to make beer from your own blend of malts and hops and a good method of improving a standard beer kit. Both liquid malt extract and spaymalt increase the body, flavour and alcoholic content of the brew.
Adding malt to a brew will also moderate the power of the hops, if this is what you need fine, if not try a hopped extract.
Liquid Malt Extract contains ±20% water
Spraymalt contains ±5% water
So if using spraymalt in place of liquid malt extract you will only need 15% less of the amount