The trail proper switchbacks steeply uphill offering better and better views of Eklutna Lake. The end of the trail is the second bench. This is a great hike if you're already camping out at Eklutna Lake. Otherwise, I wouldn't make a special trip unless you plan on continuing on the primitive trail.
Once you get to the second bench, you can continue up towards your right to Pepper Peak which is a great hike as well.
To continue into the Twin Peaks valley, head into the gulch and work your way towards the two identical peaks (and No!-it's not named after the TV show). Most of the hike is sub-alpine tundra. The view of Eklutna and the mountains is incredible. You can get to 5000 feet with not too much difficulty and if you're lucky like I was, you'll get a chance for up close views of dall sheep.
When I did this hike, it became a very cool moment for me. I was at about 5200 feet when over 50 dall sheep arrived in the valley below. I had to walk through the middle of the herd. It was an incredible experience for me and I hope you can have the same opportunity.
The Falcon Guide and the maps make the primitive trail to Twin Peaks a little confusing. First, cross over the creek and the gully. After a little ways, you'll cross a small stream. Head left and up toward the hill and not right, towards the downward slope. Basically there is a loop that goes around the inner rim. There is really no need to to do this loop as you can head down anywhere and pick up the trail.
If you're going to go to the very peaks, don't bite off more than you can chew. From the last part of the trail, it looks very doable. Then when you're halfway up, you realize just how vertical it is. Think carefully about your approach. I didn't and had to crab it on my butt to come down because I was unable to stand. It was a hair raising experience.
Do this as a day hike. There is no flat ground anywhere. I wound up scrunched up at the bottom of my tent the next morning.
A state campground exists at the trailhead on a first come, first serve basis.
Please go to the trail description for Eklutna Lake for more information about the entire area. There is a lot to do and see here. It's a great place to hang out.
There is a $5 parking fee (bring exact amount). The price for an annual parking pass is $60. You can purchase a pass at the Federal Building at 4th and F or the Atwood Building on 7th and E, 13th Floor.
If you're heading back to Anchorage, take a quick side trip and visit the Native Russian Church and Cemetery. Continue straight for a few miles instead of taking the left onto the Glenn Highway. Stay outside the fenced area and be respectful of the premises.