I just started with Lowtrades yesterday, and will be wiring in some funds tomorrow(stuck at work unfortunately!). They seem to be a good broker from what I can tell and what I've heard.
Upsides: Cheap commissions...thats they're big selling point. Unless you can afford a $5000 minimum for freetrade.com, Lowtrades is the cheapest thing around.
Downside: It took 2 weeks for them to open my account. So once you're serious about them, send the stuff right away. That way you can trade sooner. Also, their interface and trading system isn't designed for a novice. You need some familiarity with a few terms, but a quick Google search will help you find any terms you're not familiar with.
Overall...I'd say go for it. The commissions are at a very good price, and I think its a good choice. Check out the Sub-Penny message board for a lot of comments about Lowtrades.