Hi Phil, I've been playing the minis game in tournaments pretty much since the game first came out. I think the new 2.0 rules are great. They are definitely different and offer a preview of what 4e combat is like.
The game is fairly balanced. There are a lot of good tier one warbands to choose from and many of them don't require rare figures. In fact, there are a few that only need common and uncommon figures.
That said, some figures are better than others so don't expect to just throw together any 10 figures for a warband and expect to take on all comers. Just as in other collectible games, looking for hidden synergies is generally the path to victory.
There are two types of Constructed play. One is Vintage: This includes all of the figures ever produced by WotC that have 2.0 stats. The other is Standard: This is a more fluid format with sets that rotate in and out. Currently all the figures that have 2.0 stats are legal in Standard. Nothing will rotate out until 2009.
There are two types of Limited play. One is Sealed: In this format, you build a warband from two boosters. There are no faction restrictions. The other is Draft: In this format, you open a booster dump it out and draft one figure from it. The next player then chooses. This continues until all figures are taken. Then the next player opens the next booster. It's similar to Draft formats found in other collectible games.
You can get full rules for all formats on the DCI website. If you have specific questions about the game, I suggest going over to
http://www.hordelings.com. It's probably the best D&D Minis forum around.
Enjoy...
--sam