I had run across this trail online a while back, and finally went up to check it out. It's a pretty decent trail with a few problem areas. I suspect if they would round the city council up and let them ride the length of this trail on bicycles, things might be a little different on the trail. The trail surface is very fine gravel, suitable for any "average" bicycle, no mountain bike required. Generally smooth, more so towards the south end.
A map of it is here:
From the south end, start at Burl Street. From the north end, start at City Hall.
I started at Burl Street. There is not an exit from I35 for Burl Street; you exit at Swisher and go up the service road to Burl Street, and down to the trail. There is not a marked parking area for the trail, but there is room to park off the unnamed branch street that turns left just before the trail. I'm not sure if this is a legal parking place, or if you're parking in someone's yard, but at least my car wasn't towed.
Where the trail crosses Loop 288 (I think that's the road it was), they have it blocked off on the north side of the road due to construction. The trail just comes up to the road, away from an intersection, and I'm not sure how you crossed there before they blocked it off, as traffic backs up past this point from the red lights. It's rather tedious to work your way around, and there are no signs showing a suggested detour.
Where the trail crosses S. Woodward Lane/ Colorado Blvd, there are stop signs placed as though you go straight across, then signs directing you down to the Spencer Road crossing to cross at the crosswalk. Except you can't easily navigate the narrow sidewalks and push the "walk" buttons from a bicycle.
From the south, the trail comes up to Jackson Street, and appears to go across it, only the trail is dirt on the other side. Then the dirt trail just terminates at a concrete-lined creek. There is another dirt trail going from the other side of this creek on to Prairie Street. But you need to dodge over a block or two to get across the creek. Once again, there are no signs indicating this; you just have to know or you get to ride to the end of the dirt trail and turn around. Pull up this area on Yahoo or Google maps and you can see the arrangement on the aerial photos. (The trail is shown as a railroad on the maps, visible as a trail on the aerial photos).
There is nothing at either end of the trail to signify the beginning or end of a trail; no "trailhead" as such. On the north end, following the trail just puts you onto a sidewalk near City Hall. On the south end, you come to Burl Street, with a stop sign at the road, a crosswalk, but no trail on the other side. There are no trail maps posted, although the trail itself is generally well signed with mileage markers, trail signs at the intersections, stop signs at the cross roads, etc.
All in all, the trail surface is in pretty good shape. There was a little dip across the trail near Jackson street that oughtn't be there, and for some reason a section a 100 or 200 yards long is single track. Right before I got back to the south end, I had two flats, I suspect from stickers, although I haven't torn them down to see yet.
On my ride up and back, I didn't see any other bikes- a couple of joggers, a couple of dog walkers, a couple of pedestrians, but no bikes. Did see a nice-sized snake, though.