The Castine 140 has been a good weekend tourer. It has a good gear capacity and is a stable boat that tracks well. I'm 6'3" tall and around 205 lbs and it fits me well for a 14 foot hull. Loaded with 60 pounds of gear it maintains good trim and still moves through the water easily. I have not taken it on any river trips yet so I can't speak to how it does in easy rapids.
I got the boat because I happened to be driving past the Old Town factory store in Old Town, Maine-and who wouldn't stop to look around, right? I'd been looking at kayaks in this general size/class and this one had a good price, so I gave in. I also sat in, but haven't paddled, a Castine 145. It felt huge compared to the 140 with much greater volume due to the higher deck. Even with my height, the 145 felt too big so I opted for the 140. I've been happy with the choice.
As noted the boat has good storage in the fore and aft hatches, has bulkheads to seal off the areas, has good deck rigging, and a pretty good amount of space behind the seat. The seat itself is comfortable although I get the spray skirt caught on the higher back fairly often and have to adjust to get it onto the coaming. Foot pegs adjust easily as does the seat back and bottom. I haven't done anything to test how waterproof the hatch covers are, but they seem to seal well. The slide-out storage box under the fore deck seems kind of cheap and hokey. It has an o-ring seal on the lid, but I sure wouldn't trust it with keeping a phone dry if you flipped. The latch also pops open too easily as noted by another reviewer.
Overall the Castine 140 is a good, steady boat that will do well on day trips and has the capability to take on longer adventures on lakes and should be OK with class I-II rivers.