It is lightweight and, on the whole, well constructed.
I like the baffles that keep it from ballooning out so it stays flatter.
I like that the top can be completely opened.
The flow rate for the bite valve is good, once you get used to using it.
The BAD stuff:
The bit valve takes some getting used to, it's at a funny angle which doesn't make sense, the twist lock is impossible to do with one hand and hard to do even with two.
But, the biggest problem, which should not have made it through to production is the quick connect attachment for the hose. The concept is good as it saves you having to rethread the hose each time you fill up, but the quick release button is so sensitive you hardly have to breath on it and it depresses separating the hose. With all your kit stuffed in your sack and bouncing around when walking, or worse when cycling, this is not just likely, but inevitable. Fortunately, it has a valve on the reservoir side so it won't dump the entire reservoir on your kit but there isn't a valve on the hose so the contents of the hose is free to dribble out over your belongings unbeknown to you - until you go for a drink which doesn't come, and then have to go through the faff of opening your pack to reconnect it.
Osprey have clearly thought about this issue, but haven't done satisfactory testing; they have designed in a plastic guard next to the giant button but this is frankly useless which would have been obvious to anyone the second they looked at it, if they actually cared. This NEEDS a redesign in order to be a viable product, in it's current form it makes the whole system useless and a waste of £30. It's a shame that one feature that is meant to be better, let's the product down so comprehensively, because it's definitely worth more than 1 star otherwise.
Pulling a bottle from the side pocket remains a better option than this.
Osprey Customer Service,
Thank you for taking the time to write a review on our Hydraulics 2.5L reservoir.
We have passed this feedback on to our design team for consideration.
We haven’t noticed the quick-connect releasing too easily before, as the tension of the release button is designed to be relatively high. It sounds like you may have received a faulty component which is releasing with minimal pressure. We will, of course, be happy to replace this for you. Please contact our Guarantee Team to ask for a new component.
Osprey Customer Service