The US is no longer an imperial power to the extent of truly trying to exert direct power over other countries permanently. The US no longer takes countries and makes them its own territory as it did with the Philippines over a century ago. US imperialism, if we can call it that, is now generally exercised through diplomacy, economic power, and sometimes more temporary military actions.
Is this a good thing? To some degree, yes. The US at least tries to bring human rights and democracy to other countries. Of course, it is not perfect in what it does, but it is generally focused on something other than simply trying to take power and wealth for itself. If the US abandoned this role in the world, it is hard to see any country stepping in and doing more good and less bad.
A major negative about US "imperialism" is felt by Americans. The US has to spend a great deal of its resources on military power and on various kinds of foreign aid. This is money that, especially today, might be spent improving our own country but is instead spent on our role as the dominant power in the world.