Solid, depending on what you want.
I bought this bladder for a week long backpacking trip. It performed well but the water in the tube froze overnight. It would take about a hour or two for the ice to thaw. Also, inserting the bladder into your full pack can be quite a challenge. Osprey makes bladder with a stiff plastic lining that makes it easier to insert the bladder into the pack.
1. Great for Spring, Summer and Fall trips but put the bladder in an insulator for winter.
2. Load the bladder before you pack your bag. This might mean having to repack your bag every time you refill the bladder.
Overall, solid bladder that performs well.