You definitely only want to buy this product if you have the need. I'd say that need starts at about 40 assets. Less than that and you may be wasting your time with a a product that is overkill. We use it for about 1000 assets and it is a lifesaver. I couldn't imagine managing the assets manually.
It is not a perfect solution. I don't believe it is the best software for some of the components it offers but I do like and appreciate what it does offer. It offers complexity and a range of features for a company to take advantage of if planned and implemented properly.
I cannot remember the names of different software I evaluated in comparison at the time but I do remember Manage Engine AssetExplorer offering more useful features and the P.O module also being a diamond of a find.