I did this trail end-to-end yesterday as an out-and back from the southern end (no official parking at the trailhead but two supermarkets nearby could be utilized).
Overall in good to very good shape.
The non paved sections are OK for all type bikes except perhaps not for road bikes if the trail is wet.
The on-road sections are generally well marked by Empire State Trail (of which this trail is a part) signage.
Informative signage along the way.
It's not exactly a flat ride. My cycling app had it at over 1800 feet of elevation gain for the out-and-back.
Tip: About 6 miles from the southern end is the Hudson River Skywalk over the Rip Van Winkle Bridge with great views of the Hudson River and the Catskills.

As you come into Utica, there is a construction area that would benefit from some temporary signs. You ride down a small hill into a wide open area. Once you do this, you will find that there is no sign that should direct riders to go left. Going left will take you across railroad tracks, and to one of the locks. You cross the lock and rejoin the trail. If you make the mistake and take a right instead of going left, you will be forced to ride into Utica on a busy road. Other than needing a sign at this location in Utica, the trail is amazing. We road from Syracuse to Albany.

Loved this ride. We rode from Columbia Plaza in EG to Nassau and back. Casual riding took 1 1/2hrs to get to Nassau (and much longer to get back- as it was our first ride this year-do we were tuckered out!). Lol. Miller RD (exit 10) Schodack has a convenient store which is about 1/2 way. So a great “pit-stop”. As was “smilees” ice-cream in Nassau and a Taco place “Diablos ?”sp across the way in Nassau.

My wife and I tried this trail because it is a fairly short drive to Hoosick Falls. It is NOT your typical bike trail. It is gravel (hard packed crushed stone) but not difficult to ride on. We parked in a lot in town at the middle of the trail, rode north which was very nice and not too long. The north end is a bit desolate. We rode back and attempted to continue on the southern part, however it was not marked at all and we could not find any visible "access" point. We eventually made our way through the town and found a sign pointing us toward the trail.
This eventually brought us to the southern end of the trail near some little league ball fields. We rode northward again on gravel for about a mile when the gravel abruptly stopped. We spent 5 or 10 minutes contemplating whether to continue or not. Ahead of us was just grass, but not something that looked like a trail. After about 100 yards it became a mowed grass path which was definitely an old railroad bed, rather high with the river to our left and a ditch to our right. To say the least , it was NOT what we expected. This section was directly behind peoples homes and we were not even sure if we were on a trail at this point. It eventually went under a train bridge and came out where it was not marked at all, a few blocks from where our car was parked. To say the least, we wish we had read a review similar to this so we would have known what to expect. Hopefully this will help to inform someone else in the future.

This was moderate to difficult. But I am in my advanced 50s and over weight. It is 85% uphill, a lot of rocks. Not sure if all the rocks are from hurricane Irene or if it has always been rocky. A hiking stick was helpful for balance. My husband, same age, not over weight found it moderate to difficult, but navigated the rocks much more easily. The falls are incredible! Worth the hike.

Nice flat path for a run. Definitely not 3.5 miles as stated. It’s approximately 3.25 according to my Garmin.

I live about 7 miles from the South Londonderry trail head and only wish the trail was better suited for my hybrid bike. The first 3 miles (approx) to the Winhall campground are in bad shape (dirt festooned with rocks, roots, ruts and mud puddles). I don't know when the article summary was written, but I have a different idea of what "well maintained" means. Those with mountain bikes or fat tire bikes should have a much easier time with it though.
The trail ride is sandwiched by a campground road for a couple of miles. It's asphalt, and other than navigating several speed bumps, is an easy ride to another dirt path on the Jamaica side. It's in better shape than the South Londonderry portion. It's not in great shape for riding either but very manageable.
The two dirt path portions follow the contour of the tree lined West River. The view is particularly vivid, particularly in Autumn, and a favorite spot to hike with my dog. As a bike trail though, it needs work.

2021: Biked the Erie Canal trail from Buffalo to Cohoes. Well worth the time. And mostly a very pleasant experience, with just a few caveats. Trail improvements are ongoing and signage along the trail is not always up to date, so check your route carefully, especially where it is on-road. The initial section from downtown Buffalo is grungy city streets, but that improves with a great, mostly off-road trail all the way to Lyons. Lockport to Spencerport is fairly exposed, but from there on to Lyons is generally pleasantly green and shaded. From Clyde to Port Byron and through Syracuse were onroad and not always clearly signed and were the least pleasant. From the east side of Syracuse all the way to Cohoes was a delightful and beautiful ride, with the exception of finding one's way onroad and with poor signage through Rome. All in all (despite my caveats) a good, local, human-powered bucket-list endeavor, with thanks to all the communities along the way and everyone maintaining and improving and filling the gaps in the trail.

We rode from this trail on hybrids and enjoyed the experience. Was pretty flat with a few spots of incline/decline. The pavement was generally good, with a few spots with bumps or cracks from weathering. There were a lot of road crossings so we had to be careful. Very scenic, we rode thru a couple of towns, and saw a lot of older abandoned factories (Louis Meyer Make Gloves). Seems like a great local resource.