There have been good parts and bad parts to Mass Effect 3's DLC, IMO.
The good is the microtransactions. The beauty of it is that it doesn't give you anything you can't simply get by playing the game more. People who want to get ahead and have the money to pay for it can, while people who don't have the money are not really worse off. It subsidizes the multiplayer content so people who wouldn't normally pay for stuff like map or weapons packs (ie me) can enjoy it at no cost. And due to the way Mass Effect 3 multiplayer works, it's not a "free multiplayer, pay to win" situation -- if someone on your team is packing top tier weapons thanks to paying for them, that's a good thing. Ultimately the microtransaction system that BioWare put into place for ME3 multiplayer is, IMO, genius. Also good was making the Extended Cut for free. There was probably a very tense discussion in the BioWare/EA offices before they decided to make that content free. Likely the only reason they did that was because they knew charging for it would just make more people upset, and the point of the extended cut was a peace offering to appease gamers who felt betrayed. I certainly appreciated the peace offering.
Not so genius was the day 1 DLC. Now, it may be that the "From Ashes" DLC was put into production after ME3's production was locked down, and it was legitimately developed separately from the main game. I get that. The problem lies with comparing it to BioWare's own past DLC. With Mass Effect 2 (and Dragon Age: Origins, for that matter) the first DLC character was free (well, free as long as you bought the game new). Mass Effect 2 had a second DLC character which they charged 560 points ($6.99) for. Then, Dragon Age II had a first day DLC character which they charged 560 points/$6.99 for unless you pre-ordered the "signature edition". Then Mass Effect 3 had a first day DLC character which they charged 800 points ($10.00) for. That's a sixth of the price of the game for much less content. It just seems that BioWare (well not BioWare really, EA executives are responsible for pricing) keeps trying to push the envelope with how much they can price gouge for DLC.
As for DLC in general, the basic problem is that it tends to be overpriced. Also, they don't seem to ever drop prices on DLC -- Mass Effect 2 sells for $20 now but its Lair of the Shadow Broker DLC can only be bought for $10. But I don't think that means it should be free or anything. I enjoyed Mass Effect 2's paid DLC content and didn't resent the fact that I had to pay for it (well, the story DLC, not the weapons packs). As for ME3's upcoming Leviathan DLC, I'll reserve judgement until it's actually released.