As I've mentioned on many occasions, I have been, at best, an indifferent user of miniature figures in my roleplaying game campaigns. In ancient times, when I started playing, we all owned miniatures, at least for our player characters, and often put them in the center of the table to represent the party's marching order. I also owned lots of monster minis, which I'd sometimes (though not always) bring out in order to show what the PCs where facing. I even owned a set of cardboard cut-out dungeon floor plans -- by Heritage Miniatures, I think -- that I'd occasionally lay down in order to show the basic layout of a dungeon, though we often dispensed with this, because it could get tedious and because I didn't have enough floor plan pieces for all but the simplest dungeons.
All that said, I can't say that we ever really "used" miniatures in a significant way. They were mostly cool "toys" rather than an integral part of our gaming experience. In this respect, I am more sympathetic to those who argue that minis aren't a necessary part of the old school gaming experience. Back then, nearly every gamer I know purchased miniatures but none of them really used them except as very limited props. What's interesting, of course, is that I remember reading many articles about D&D in newspapers and magazines -- this was at the height of its faddishness, remember -- and many of them were accompanied by photos showing gamers hunched around a table covered in miniatures. Whether these photos represented the reality outside my little corner of the hobby or (as I suspect) just made for a nice image to accompany these articles, I can't say for certain. For me, though, minis were absolutely unnecessary.
So, when I began my Dwimmermount campaign over a year ago, I figured I'd use minis only sparingly -- and so I have. Part of the problem is that it's a lot of work to pull out all my miniatures and the dungeon blocks and arrange them in play, especially given the rather seat-of-the-pants style I typically employ nowadays. There's also the fact that, no matter how many Otherworld minis I buy, I'm never going to have precisely the right minis I need. Last session, for example, the PCs encountered two shambling mounds and, alas, I have no minis to represent them. Without that, I'll confess that a big part of my interest in minis fades.
Yet, I've seen the utility of minis in play. The reality is that, much of the time, without miniatures, OD&D combat is boring. Heresy, I know, but it's true. OD&D's combat is fast-moving and abstract and it's very easy to adjudicate when the players come up with extemporaneous tactics and maneuvers to get the drop on their opponents. However, many of these tactics only become apparent when there are minis on the table, when the players and I can both see the "lay of the land," so to speak. Without the visual cues minis provide, combat can easily degenerate into a dull sequence of dice rolls without any flair. That's not a knock against my players or a bit of self-recrimination; it's just how things often go without minis.
Consequently, I'm making a concerted effort to bring out the minis for every Dwimmermount session. I still don't think minis are necessary for old school play and I know that many would rather not be bothered with them. For this campaign, though, I've found them extremely helpful in inspiring us to make the most of OD&D's combat system. If only I had an infinite budget with which to buy every miniature figure I want/need, I'd be set ...