We took the advice of commenters and went west/clockwise along the the Baden Powell Trail close to the power lines rather than follow the directions by starting up the Brothers Creek Fire Access Road. This was in order to begin the trail with the steeper incline and stairs on the Baden Powell Trail which is easier on the knees. However, this was not a great idea either, as much of the fire road is loose rock, which is not so pleasant to descend and easy to slip on.
If you do go west/clockwise, you'll hit some wooden stairs at the 15 minute mark, and then a marked lookout. Someone left an old chair you can meditate on. Minutes after the lookout we got lost by continuing up a trail that wasn't a trail (you'll know you're on it, because it goes up towards the waterfall and is not safe). We retraced our steps and then saw the hairpin turn (with no marker) we missed that leads down to some primitive stairs and a bridge over the creek.
It took 1 hour to get to the main bridge at the tip of the loop. Beautiful shady trail with waterfalls. Lots of twisted roots underfoot, and a rock bed creek to cross (it was low at this time of year). At the west side of the main bridge we took the Blue Gentian Lake Trail (the Lost Lake trail is on other side of the bridge). Blue Gentian is the nicer of the two lakes, and has a picnic table—perfect time and place for a lunch break. It's pictured above. This side loop detour took 1 hour. Map that includes lakes loop.
The return part of the main loop took another hour and 20 minutes. As I mentioned, much of the road is loose rock, but also has some flat spots. Whereas the scenery on the west/Baden Powell section is gnome country (moss, undergrowth etc), the scenery on the Fire Access Road becomes less dense, with soaring second growth trees. Lots of huge old stumps, and a section of charred stumps from a 1916 fire. There are other historical reminders of logging here, such as skid roads made of logs, and the remains of a mill boiler house and steam sawmill foundation (marked, but easy to miss if you are looking down).
The view of the city above is just after the gate you go through to get to the trail.