Yes... I've been using this method the last two days to AIM with people and it works very well. It's a little clumsy to get started with, but once you have it going it works good. It's better than the beehive ap because it's faster, and more importantly, if you're logged in and someone sends you a message through AIM, you'll get notified EXACTLY like a regular text message, even when you're phone is asleep.
There is also a link on that page to a PDF with full instructions, which is very handy. It'll tell you how to log off, how to get a list of your online buddies, etc.
Downside is that you'll want to have an unlimited SMS plan because obviously, all the AIMing you do through SMS will count as SMS messages... but I figure this will be the case when iChat comes to the iPhone anyway... we'll be charged SMS rates to use AIM/MSN/Yahoo etc.
I wouldn't call it "better"... I would just say it functions like SMS/Text Messaging... so unlike using web apps, you'll get notified of an incoming message just like you would for any text message... you don't have to be in Safari with the phone awake.
iChat will definitely be the best alternative when we finally get it, but I find using the AIM to SMS alternative the best approach FOR ME so far. I like to be able to get my AIMs like a text message.