From the communter point of view, this is a tricky route if you're starting/ending in the CBD, as there's no quick bike path route to connect to the start of the trail. You can take the Main Yarra Trail (as far as St Kevin's), then head north from there (partly on-road, then joining the Yarra River Trail), and then spend another 7km on Yarra Boulevard before you finally reach Chandler Highway - something like 15km of riding to cover a direct distance of 5-6km or so. Not exactly an optimal route for daily riding.
The quickest way is on-road - up to Barkers Rd or Studley Park Rd, then on Princess St to Chandler Highway, and to the start of the trail, but these are busy roads with lots of cars and trams and all the usual hazards.
The route itself is pretty good for commuting on - only a couple of road crossings required, other crossings are handled via underpasses/overpasses. There are a couple of hilly areas, but only shorts bursts of climbing required. However, as with most of these trails, the path is only wide enough for one bicycle heading in each direction - if commuting at a busy time of day, overtaking may require patience and waiting for clear visibility ahead. And of course, the trail is shared with pedestrians, and there are a couple of sections passing "leash off" areas for dogs, so some caution is required in those areas.
For a more serious cyclist looking to get some training in, this is a pretty good route - there are only a couple of places where you have to stop, and the hilly bits are quite manageable. However, as above, there are pedestrians and possibly dogs to worry about. Also, there are lots of twists, turns and bends, you won't be able to maintain a steady speed all the way along.
For the casual rider, the trail is good, but signage could be better in places - there are a couple of places where it's not completely clear where the main trail continues. And as is often the case with these trails, there isn't much signage to tell you which suburbs you're in, or can get to on the path. Otherwise, pretty good for the casual rider, and despite being close to the Eastern Freeway most of the way, the scenery is pretty nice, winding back and forth over Koonung Creek, through some parks and foresty areas.
Finally, riding with kids. The trail would mostly be good for kids - there are plenty of places to stop and rest, and a couple of water fountains along the way. However, the hilly bits may be too much for some, especially if they haven't mastered the use of gears, and some will end up walking up them. Some of the descents will need caution too, and enough strength to keep brakes held on sufficiently. The section between Blackburn and Springvale Rds has a hilly section that is probably best avoided with young kids.
Original post on Dreamwidth - there are comments there.