2/5 stars...a below average experience. We've been to many of the groves and trailheads in the Redwood State/National Parks, and the effort one needs to put into visiting this grove is not worth it. I'm glad there's a reservation system, otherwise the number of cars would easily exceed the capacity in the small lot. The drive is 6 miles along a gravel road from Bald Hills, which takes about 20 minutes.
The hike itself is ok, but for casual outdoors folks, it might be considered a long and steep descent/ascent to access the grove. It's also not any more scenic/different than many of the other nearby redwood grove trails. The part that was really disappointing was the lack of signage/info boards about the trees in this grove, and the mysterious numbered wooden post markers all along the hike and in the grove. Turns out it's antiquated interpretive signage, but if you look hard enough online, you can find the info about the numerous markers. We also ended up reading a lot more useful information about some of the specific trees in the grove online, but this would have been far more useful to have on a sign board on the ground.
Lastly, we kind of realized there's not much of a point viewing the tallest trees, you can't tell much from 300' below. You just look up and say "yup, that's a tall tree", but all redwoods are tall. Purely being tall doesn't really create a visual impact, as even a tree 50' shorter looks REALLY tall the ground. Overall, there are FAR better trails and groves throughout the park, I would completely skip this for the amount of effort needed to get there.