In a lot of ways a resounding YES!
After using it for about 6 months I am finding i can achieve a heck of a lot more than I thought was originally possible. You only have to go and have a look at some of the stuff found online to see what can be achieved.
Here are some places I found really useful.
Blenderguru
Blendercookie
Blendtuts
There are A LOT of things that Blender can do that a lot of the commercial packages can do. As far as I know, the modelling side of things is practically the same. The modifiers all work on very much the same principles. And there are some things that I have been told are easier in Blender than say a $5000 package like Maya (so I have been told, I havent used Maya).
So why use Blender? Well it’s free and open source. That’s pretty much the crux of it. I think this program has definitely been written off because it is free, but I promise you, if you understand it, you can get a lot out of it.
Here are some examples of work I have been doing lately.



All this was done in Blender (with a few photoshop finesses but nothing much I promise).
Anyways give it a go. What have you got to lose?