Here's a little bit of information for everyone: Last year I started a poll here on ENworld, and another one on Dragonsfoot, asking people whether or not they used miniatures or tokens when playing D&D. Now, I'll point out that ENworld is primarily 3E and Dragonsfoot's primarily 1E, so there's a big divide in many opinions about how D&D should work.
The results for those polls? Nearly identical. Between 15% and 20% of players in D&D (any edition) use no tokens or miniatures - between 80% and 85% of people in both polls use miniatures or tokens.
Wow.
Add to that the "little detail" from the WotC survey that shows that people who use miniatures with their RPGs spend a huge amount more than people who don't, and you see why Wizards have taken the line they have.
I know I've spent about 1000 Austalian Dollars so far on these miniatures, which is more than I've spent in the past two years on RPG materials.
The silly thing is this: I don't normally use miniatures or tokens in my games. About one session in 20 uses them. I'm one of the 20% who normally runs things by ear. (However, I do play the Skirmish game, which I've found to be utterly excellent).
Of course, if you do normally use miniatures or tokens, should you buy the D&D Miniatures line?
My advice is to look carefully at the commons and uncommons in each set - especially the commons. Do you actually need them? (Because that's what you'll be getting lots of).
If you see a lot of figures you want, then that's a good set to get. If you're only interested in a couple of rares, then the odds are against you. Look for a non-random alternative.
The D&D Miniatures line works best for those who run a traditional wild & woolly D&D game. Where any sort of monster might be encountered - Kuo-Toa, Drow, Elementals, Dragons, Undead. Oh, and Orcs and Goblins. Each set has a different mix of figures - look at the set lists and see if you want figures from that set.
I know that, as a RPGer, I'm not that excited about Archfiends. The monster common list is as follows: Githzerai; Dread Guard; Duergar Warrior; Snig The Axe (a goblin); Zhentarim Fighter; Gravehound; Warrior Skeleton; Cultist Of The Dragon; Cursed Spirit; Gnoll Archer and Orc Raider. The only one there I'm really interested in is the Gnoll Archer. Because I'm going to be using the set for skirmishes as well, it doesn't bother me so much, though.
But I'm not everyone. I don't think Archfiends will do as well as Dragoneye, because it's more limited in its usefulness. It seems more aimed at the FR player and Skirmish player than the general D&D role-player. I may well be mistaken.
I'll leave you with this:
Merric's Law of Miniatures: Non-Random Packaging, Cheap Prices, and a Large Range of Figures: Choose two.
Cheers!