I went to REI today to buy a water filter. We're going backpacking next weekend and had said I would bring one. (It's one of those items that everyone in the group doesn't need to own, not like socks.) I had decided on the MSR Hyperflow. It was Backpacker's "best buy" filter in their 2008 gear guide, and for what looked like good reason; it weighs less than most other filters, and it's supposed to be fast and durable.
Turns out REI doesn't sell it in their Nashville store, and online ordering wouldn't get it here in time. I was surprised at first that they didn't have it in stock, but maybe its slightly high price turned off local buyers. The Nashville store is pretty small, although they are expanding - at this very minute in fact. Rather than settle for another filter, or trot over to Cumberland Transit to see if they had it (I have a store credit with REI I wanted to use), I ended up going with the "other" choice in safe water, Potable Aqua tablets.
They're iodine, and iodine water is yucky. However, they have a version that comes with a second pill to neutralize the taste. We'll see if that works: I want to taste water, not mask it with Kool-aid or Crystal Lite. The other drawback is it takes 30 minutes to make water safe. The upside is that it doesn't require maintenance, unlike a filter. It's also much cheaper ($10), so if I hate it, I can throw it out or give it away. I don't think I'll be a fan, but trying it won't hurt.
By the way, if you read REI's customer reviews for water filters, you'll never buy any of them. Each one seems to be split between "this RAWKS" and "this product doesn't work." I seriously don't see how any one product, let alone an entire category of them, can have such differing reviews. With iodine, now, some people like it and some don't, but it's solely because of the taste. No one argues over whether iodine works or how easy it is to use.