Demon of the Well
Dragonsbrethren: Not all of the maps are like Dragon Hunter's (although if you didn't like this one you probably won't like his map 15, either); some are much smaller and tighter, a handful are much brighter, and many have a different combat style. That aside, I think that sometimes it's a worthwhile intellectual exercise to give a chance to/play through something that's evidently not really up one's alley. I got almost no direct enjoyment from playing through Zone 300 when the club did that one, but I consider it to have been an experience worth having anyway, because it gave me an opportunity to think about gameplay/design decisions that I feel do/don't work from a novel/different angle.
Anyway, on with the show...
Whitemare Map 01 -- Ice Canyon - 100% Kills / 100% Secrets
While perhaps a bit unorthodox for a map 01 from a gameplay perspective, this is a fitting introduction to Whitemare's aesthetic angle--rather than starting in a frostbitten techbase or the like (that will come later in the WAD, incidentally), you're in a dark icy tunnel system with glimpses of a snowy mountain range visible through apertures in the roof, and soon enough you find yourself stumbling out into vast wintry valleys and riverbeds with severe foothills and crags (some ominously capped by strange signal fires) beetling up around you. While there are a number of distinct sub-themes in Whitemare, the ones that most dominate are open arctic landscape and mysterious frozen caverns, and both are introduced effectively here. For the most part I think it's a very solid visual presentation--macro-tiling over huge swaths of natural landscape doesn't bother me so much in DooM, and the sector-based bump/terracing effects (chunks of ice in the river, different ground levels in the blue key valley, etc.) coupled with the generally wide open spaces and panoramic mountain scenes (which really constitutes the bulk of the detailing in the level) give the proceedings a very clean look and a distinctly fresh-air feel. There are a couple of visual errors to be seen if you really look for them--for instance, some of the ice shelves around the waterfalls in the blue key valley have water flats on their top surfaces despite not being part of the falls/not having fall textures on their sides--but these are generally subtle and don't detract much from the overall impression.
As to the gameplay, well, vast open spaces, lots of mid/upper-tier monsters, and a sequence of arena-style battles is probably not what most people think of when they think of 'map 01 gameplay', for sure. This is presumably a natural consequence of the fact that the maps were, as Memfis says, originally designed to be standalone offerings, rather than as parts of a measured progression in a larger set. I don't think there's anything wrong with deviating from the norm in matters like these, though, and despite the nature of the choreography, overall I'd say the map is still certainly easy enough not to seem like the mapset is throwing you into the deep end from the outset. Sure, there are lots of revenants and mancubi and whatnot, but you get ample weaponry, several timely soulspheres, and tons of excess space to run around in to fight them, and so the sum effect is more like it's a nice jog rather than running a marathon or whatnot...if anything, some of the fights seem somewhat understaffed by monsters, particularly the blue key valley. I do like the chainsaw-centric start (used it on everything up to and including the pain elemental, with some buckshot on the side for the hell knight), as well, gives the opening moments a different feel than what we're used to. I will agree that spider mastermind doesn't make much of a contribution, though--essentially all you end up doing is leading it back to the blue door chokepoint and methodically SSGing it to death, at minimal risk. Incidentally, I think I only took three hits or so in this level, and one of them was that poor zombieman's final act of defiance.