There is proverb about "not seeing the forest for the trees", and in the case of the Redwood, this can be taken quite literally.
There are some extreme, perhaps even humorous examples of how large Redwood trees can be. There are several Redwood trees that you can drive a car through. There is one Redwood tree where an entire house has been built inside of a single downed trunk. There are superlatively large trees that can require over a dozen people holding hands to encircle. Even if you have never been to California, you have probably seen these pictures, and heard the lore about these massive trees.
Redwoods do not grow as single trees, to be roadside attractions. They grow in forests. Not all Redwoods are novelty-size large, the Redwood forests contain very large trees, and also "medium sized" trees. An average Redwood is still very large, probably the size of a large Douglas-fir, but might not seem awe-inspiring to someone casually driving past it. But it is these "normal" Redwoods that together make up the Redwood forest ecosystem.
What is this ecosystem like? Redwoods grow in the temperate rainforest of the Pacific Coast. These forests start in the Alaska Panhandle, run down through British Columbia, Washington and Oregon, but only at the very south of the Oregon Coast do the Redwood forests begin. In many ways, they are not much different than other areas in the temperate rainforest belt. They have moderate temperatures, with rainfall and humidity concentrated in the winter months, and with dry, warm (but rarely) hot summers. Frosts are uncommon, as are temperatures above 100F. The forests are dominated by pine forests, with deciduous trees, such as alder and maple, being common as pioneer species on disturbed ground or along rivers. There are also other ecosystems, such as wetlands and prairies, interspersed between the forest. For the most part, a redwood forest looks like a Douglas-Fir forest, only more so.
What it is like to actually be in a redwood forest, or even a smaller grove, is hard to describe. Redwood trees are hard to photograph: pictures usually don't capture the scale of the the trunks, so what is a grand view in person just looks like a mishmash of trunks in a photo. Intact Redwood forests also usually have little undergrowth, because the trees shade out smaller plants. They also keep an insulated layer of air, so it is usually several degrees warmer or colder inside the forest than it is outside of it. The air is also very fragrant, and sound seems to be dampened. Being inside a Redwood forest is a hard experience to describe, and it is a step above the impressiveness of the size of an individual tree, even though that is quite impressive.