I have played in five of them and here's my experiences with them. I hope they will help with the design of future wilderness areas. And I must mention I like ddo wilderness a lot because they are amazing while waiting for an lfm to fill or when you have too little time or no time frame to actually run a quest.
Subterrane. It's by far the most interesting and beautiful of them all, even though I generally dislike underground 'wilderness'. Unfortunatelly, it's not really 'epic', more like raid heroic. The max minimum level is 21 and as a matter of fact is right seeing as how if you enter at level 20 with destinies or at 18-19 on a properly geared/built toon you'll have a walk in the park. Then again, isn't wilderness quite more casual than a dungeon? I would seriously hope to see this reworked into a properly epic wilderness and possibly the xorian side expanded.
Cannith. Ah, good old cannith. For me it's a direct example of how wilderness should not be. It's right up there with steam tunnels. It's very small, it has very few mobs, it's very unexciting. It has some good loot but is outleveled almost immidiately. And, bottom line, it's boring. All it really serves is extending the time of lob/ma lfms. Just like subterrane, it was admitedly designed in a era that ddo was a different game. In my mind, if anyone ever bothers improving changing this it would be to add teleporters or scrap it completely.
Gianthold (Epic). Damn this place looks ugly. Certainly, it's a desolate wasteland that suffered apocalyptic destruction. A great improvement over heroic wilderness. More mobs for one that occasionally gang up on you and threat you with real danger. It even has random dragons! Actually, it says it has random dragons. To see a dragon you have to search and search and search... If it was just two of the rares being dragons, I'd understand. But you went and put up and actual 'slayer' for dragons. Kinda reminds me of 'portal fragments' and 'orthon parts' from shroud. Add damn random dragons, not just the two rares! I am tired of seeing the same two giants in all the places where 'rare' encounters might spawn. Or rename your 'rare' encounters into 'mythic' encounters haha. Oh, and the rares here other than the dragons are kinda... unispired? Especially when you get a whole bunch of 'totems' and the rare that wants them doesn't appear anywhere. More dragons please. Did I say more dragons?
Three-barrel cove (Epic). Remember what I was saying about dragons? Exactly the opposite happens in 3bc. There's always a ship, usually two. They can one shot you if you're not geared AND careful. They can one shot you if you are. They have way too many hit points to fight without balistae even on a furyshotter or artificer. They are almost always out of range of 'shot' runearms and many spells. Granted, the first time you jump onto one and go blow it up from the inside is sooo cool. But not the 100th. If they spawn so much, why don't we have an 'airship slayer'? You guys did this the wrong way around! Switch how often these spawn with how often the dragons spawn in epic gianthold and you're working towards something. It's a shame really as the heroic wilderness is probably the second best in the whole game. The rares make sense but are totally run of the mill, even worse than gianthold rare encounters. My expectations where high and were not met at all.
* I confess it might be due to the fact that fighting a dragon is a lot more interesting and exciting than fighting an airship. Both in theory and ddo practice. Precious cargo does a good job of that (if it was one fight and not seven almost exact repeats). The airship fights should have been in a quest.
Thunderholme. So I started exploring this place. It looks like an old dwarven city would. Again, i dislike 'underground wilderness', it feels confined. The rares are cool, the area is nice. I liked the small underdark part. Then a person joined my lfm, then another. Then I was reminded it's a raid instance. Then suddenly we have twelve people, thirty(30) mobs spawn per room and I feel like I'm playing a 3d shoot-em up game! Damn those battles are so exciting! At some point we opened a door at the very bottom and we had like fifty mobs on the screen with the couple of draconic sorcerers partying like it's a eat-all-you-can buffet! You can rack up the kills so fast it's crazy. I've heard a lot of people complain about lag in such situations and thankfully I didn't have any at all there.
Epilogue: Wilderness main point should be exploration and random encounters. Secret areas, hidden places. Not journals please those are lame. Once exploration is done, lots of people splitting up and racking up the numbers, or tons of mobs in one place so you have to stick together to mow them down. Scaling here should be more mobs, not more hit points/different mobs. Large areas. Rewards like thunderholme and to a lesser extent 3bc so there's interest in the loot.