Does just what it's supposed to do
I bought one of these at O'Hare, when my cell phone gave me a low battery warning as I was waiting for my plane. No time to plug it in, and I didn't have a car charger cable that I could use in the airplane. So, I grabbed one of these just before I boarded the plane. I used it to make one last phone call, than threw the whole thing in my briefcase. My phone was fully charged an hour or so later. I keep it around now as a backup, in case I get a low battery warning at a time when I can't charge.

Energizer Energi to Go Instant Cell Phone Charger
My husband had to go to another state for 3 days for a family emergency and we were down to one cell phone charger. I told him to take it with him since my phone was fully charged and I don't talk on the phone much. That same day my phone was down to one bar (of course!)...not good since we dont have a landline and I have 3 little ones. I started to imagine all of the worst case situations all evening. The following morning I put the kids on the bus and drove down the street to the local Rite Aid, crossing my fingers that they might have chargers. Thats when I spotted this! There is an open section on the back that allows you to connect your phone to see if it fits. Mine did,,,yay! It was $20 which I thought was a bit much but I was in a jam and would have paid more for it Im sure. I opened it when I got to the car and began to charge my phone right away. I let it sit for around a half hour when I got home and Voila! A fully charged cell phone! It does exactly what it says.

Works for me
I feel for the reviewer who had his Garmin fried, but I thought I'd add a more positive review since it has worked well for me with a TyTN II smart phone (AKA the "Tilt"). I've used it on long plane flights to get extra "battery milage" while I'm watching videos and listening to mp3s. So if you have a Tilt, you can be reasonably sure that one of these will work for you. If anyone finds otherwise, please post here. Also note that although the blurb says it requires Energizer E2 batteries, I just use it with regular Costco Kirkland brand AA alkalines. I haven't tried it with rechargeable AAs.

Not a good idea...
1. Batteries make poor contact with the charger unit and require a lot of 'juggling' to get them in position.

2. Unit is flimsy and does not stand up to daily use.

3. Whatever voltage it puts out, who knows - it fried my Garmin 360 (which charges through a mini-USB connector) within seconds.

Caveat emptor...

Piece of junk
I bought this in an emergency and I was excited because it was on clearance for $4.50, now I know why. I followed instructions and it just did not work. I was very annoyed as I needed a charged phone! Well later that day I went home and tried different batteries. Still Nothing. It wasn't the batteries that were included because I put them in something else and they worked fine. Although it was annoying I guess I can't be that upset since I got the lithium batteries out of it for pretty cheap, just don't try this charger.