Things to consider with these stations (or, what I would think about):
1. Does it alter the look of the Wiimote, and are you ok with that? I.e., is having your battery cover be potentially a slightly different shade of white and/or having a gray rubber cover (such as Nyko) going to bother you? It's something to think about.
2. They won't work if you've got silicon skins on your wiimotes.
3. If they charge via USB only, then they'll only charge with the Wii is turned on. I don't know if this means they'll pull a charge when the Wii is in standby or not, and USB charging doesn't seem as appealing to me as charging straight through an outlet.
4. The battery packs have a potential to wear down over time and ultimately become useless, and right now there's no real way to determine how long that might take. Which means there's a chance you could have a dud in a few years. Course if you paid $30 for it and it lasted that long, that's better than potentially hundreds in batteries.
5. Does it change the weight of the Wiimote substantially?
6. Do you trust a third party with power and charging?
This all said, the Nyko station seems nice. If you can get over the fact that it changes the battery covers, then it seems like a good product. I'm still debating if I want one or not.
The last thing to keep in mind? There was a rumor a while ago where Nintendo was said to be thinking about a Wiimote version 2, which would address a few different issues. Namely, that there was no internal rechargeable battery. Now personally, I like to not have internal rechargeable batteries unless I'm allowed to buy a replacement a few years down the road when the holding time goes to crap, as well as the fact that once it goes dead, you've got to wait for it to recharge. But keep in mind that this is a rumor so there's no way to know anything about it.
I will say that the chance of it happening are somewhat high, however. Nintendo has said releasing different colored Wiimotes is higher on their list that different colored systems.