(Revised 6 Jan 2016)
I would think hosta is an essential perennial for the northern garden. A perennial bed with hostas only can be boring (unless you are a hosta addict), but a perennial or conifer bed without hosta can be even more boring. It can add an element of large leaf texture that is not prevalent in northern vegetation (in comparison with tropical environment). The miniature Hostas are perfect for use as companions in rockery gardens where they add texture, lushness, and provide perfect refreshing compliments. It is an essential element in my shade garden. Many of the Hosta images on the internet are not representative of the foliage colour because the they depend on the level of sun exposure to a large extent. Like most popular plants (Hemerocallis, Heuchera, Acer and conifers), a large percentage of the huge number of cultivars available in the market contains minimal distinguishing ornamental attributes, and more for addicts.
Depending on the varieties, it can take full sun to full shade, and is hardy and (practically) maintenance free (except for the HVX virus). Unfortunately, it is often relatively expensive for a fair size specimen, and takes years to develop a nice clump. A young plant or a small clump often does not reveal the true ornamental value or beauty of a good hosta. It is very hardy, and I wish I can let it run wild at my cottage, but the deers really like it. Although I am not a Hosta addict, I do like to acquire a few each year since they are so useful, elegant and take care of themselves.