Garden snobs love to deride forsythia shrubs as too obvious, common and even vulgar. I have nothing against forsythia (except when it's been pruned into a bun), but I do find that in my garden, it will only bloom if the winter has been very mild. Generally, we get a bit of bloom at the bottom of the shrubs where the branches were protected by the snow. I know there are some hardier varieties, but our site is very exposed to harsh winter winds, so it's rare that we get many forsythia flowers. That's why I have just two of these shrubs on my 10 acres.
Much more reliable in early spring for us are two species of early-flowering dogwoods that are closely related, Cornus officinalis, Japanese cornel dogwood, which is in bloom at the moment, and Cornus mas, the cornelian cherry dogwood, named for its cherry-like fruits which appear in the fall (shown left).
It's not easy to tell the two species apart as their flowers are so similar, but the Japanese species blooms a week earlier than the cornelian cherry. The other main difference is that fruits of C. officinalis are not as showy as those of C. mas.
Both of these shrubs are more subtle in flower than forsythia, and for that reason, they are most effective in the landscape if you can give them evergreen foliage as a backdrop. Cornelian cherry dogwood is hardy to Zone 4, and its Japanese cousin is hardy to Zone 5.
One of my favorite garden bloggers, Margaret Roach, has some thoughts on forsythia alternatives and some good pictures at her blog, A Way to Garden, so be sure to check that out.
Margaret also touts the native spicebush (Lindera benzoin) as a forsythia alternative. I have one of these shrubs, and it's a beauty. The flowers are subtle - I hardly noticed them last spring - but, to be fair, my shrub was very small until it experienced a good growth spurt during last year's moist summer. Then in the fall, it blew me away with its fabulous golden yellow foliage. So if you're looking for a native shrub that's lovely in spring and fall, spicebush (hardy to Zone 4) is a another great choice. Margaret Roach has an amazing picture of hers in flower here. I can't wait until mine gets to be that size.