I purchased the same battery under XPAL brand--both XPAL and Energizer have teamed up and are offering same products--and there are several shortcomings.
I have attempted to charge several different devices with this, most of them with success.
1. LG VX5400 -- Charged without a hitch using a bundled tip and 5V USB connection.
2. Dell XPS M1210 -- Also charged with success using a bundled tip and 19V connection.
3. Dell Axim X51v -- I had to order the tip for this one, but it nevertheless charged great using the 5V USB connection.
4. Sony Vaio UX490 -- I had a trouble with this one. It appears that the battery is unable to natively support 16V output, as the device did not charge at all. At first I wondered if it was the tip that was causing the trouble, but after visiting Radio Shack and creating an improvised solution, it became apparent that the battery itself was the problem. To charge the device, I had to order a "Willy" cable that can toggle between 16V and 19V using a switch. I will explain more about this further down.
The "Tips for Life" program grants each product owners to obtain two compatible tips for their devices at no cost per year. However, they do charge for shipping and handling (USD$4.95), and since they use USPS Flat Rate shipping it's obvious that whatever they send out takes around a week to arrive. Honestly, I have absolutely no problem with paying for the shipping, but having to wait with my thumb up the arse was quite maddening.
Now, here is my major gripe; the Willy cable that I have mentioned above is what annoyed the heck out of me the most. There are three different types of this, 12V, 15V and 16-19V. They are basically cables with voltage regulators attached to the middle of the cables, and it seems that there are some devices out there that absolutely require these to operate, just like my Vaio UX unit. Before I found out about this, I frantically tried reading through the manual to find an answer, but to no avail. I proceeded to improvise a solution by cobbling up various pieces obtained from Radio Shack and soldering them together while assuming that it could be the tip that was causing the trouble. The improvised solution did not work, and I almost gave up since everything else was charging just fine. I fired off an e-mail to XPAL's customer support, to which they replied that I need the 16V-19V Willy cable to power the unit. It was pricey, but it worked when I got it, but it was pricey nevertheless at USD$17.95 plus another $6.95 for S&H. I am telling everyone this right now; there is absolutely no mention of this in the manual or XPAL's website, and the only way you can find out about this is through customer support. So the inconvenience and frustration of going absolute batshit-insane while trying to find a solution, having to make an additional investment and then waiting for a week for the thing to arrive drove me nuts.
The battery itself, on the other hand, is excellent. It packs a rather surprising amount of juice for its size and weight, and has decent safety features (Important!), including reverse-polarity protection (I was dumb enough to misread the polarity symbol on my UX at the first time I built the cable. Fortunately, the fail-safe kicked in and the battery shut itself off before anything happened, and the only thing I had to do was to reset it, which you can accomplish by simply plugging it into the charger and then unplugging it).
If you happen to wear cargo pants, you can fit it inside one of your pockets without too much trouble provided that they aren't too tight.
Also, the product description reads that the battery is pre-charged for immediate use out of the packaging, but the manual states, "Important: Always Charge your XPAL Power product the FIRST time for a full 8 hours before regular use." Just to be safe, I stuck to the latter. Afterwards, it only takes 3~4 hours to charge.
So, to sum it all up, here are the pros and cons;
Pros -- Excellent build quality; Packs an incredible amount of charge for its size and weight; Relatively inexpensive compared to other batteries with less power; Somewhat generous tip selection.
Cons -- It may not look expensive by itself, but additional investments for tips and adapters can be costly; Incompatibility with some devices that can only be resolved using specialized cables with attached voltage regulators; Vague instructions that will most likely leave everyone puzzled when turd hits the fan; No Mac support.
So, is this thing worth the money? I'd say, yes, it is, especially if you are a road warrior and have no wish to be glued to an outlet. Its relatively small size and light weight allows it to be carried inside a medium sized bag without much footprint. I got mine for USD$119 on eBay, so $99 on Woot is definitely not bad (In fact, I might go ahead and grab another one on Woot today). Just be sure to be ready to fork out some more in case you do get stuck with having to buy additional tips and adapters. If you are a casual portable device user and don't suck up electricity like air, then please move along and never look back (Or you can probably get XPAL's smaller capacity batteries for less cost).
I hope that this mini-guide helps for decision-making.