My wife and I have lived at River Crossing for almost two years, and even with a management change these are among the best apartments in the Nashua area. We're only moving out because our jobs are now both in income tax-free NH. This is a quiet and well-maintained community with ample living space in both one and two-bedroom units and generally responsible management.
The four buildings were converted from garden style condos in the 1990s and have been renovated since then. Kitchens are newer with full-size fridge, oven and dishwasher. The building is very energy-efficient; our electric bill never goes above $50 a month, even with electric heat in the winter. Our corner unit gets excellent airflow and requires almost no a/c.
For commuters, getting across the Tyngsboro Bridge during the afternoon can be a pain, but there is surprisingly little traffic noise. There is plenty of tenant parking; two cars are allowed. Snow removal is prompt and thorough during the winter months. Landscaping is good and the grounds are almost always clean. (We don't have a dog, so I can't speak to the poop situation.)
Management is new (Heritage Properties of Lowell MA), and generally a step down from the previous in-house management. Office hours have been reduced and the maintenance is now shared with other Heritage properties. Routine maintenance requests are hit-or-miss, your unit will get fixed but not necessarily right away. Emergency maintenance is still good. Hot water is included in the rent, but in the "C building" (#2) has been erratic lately. Management claims this is the third water-heater repair, but the problems persist. My advice: shower quickly or at the gym.
Overall, River Crossing is a nice rental community in a much quieter setting than most Nashua apartments. The rent is reasonable for the area and amenities. I'd recommend it.