I like the idea of garrisons. I'm not sure what the general response has been, but I've had a few thoughts I wanted to put out there.
From the sound of it Garrisons are meant to be a feature where you can't get every building and npc and whatever other features all on one character. Which to me sounds like choices. Choices are pretty meaningless if you can choose all options. This was one of the big appeals of professions when I first began playing way back in vanilla. In fact, back then when it was really hard to level alts, and farm up everything to do all the various professions, there was alot of community built on trading and sharing of skills. In the last few years, it seems everyone has developed a small army of alts so each of us can have all the professions. It seems appealing to have all the professions, but I've decided it actually makes the game less fun not finding friends, guildies, or even strangers (afterall, can't make friends if you aren't meeting strangers). How does this relate to garrisons?
Well, I think Garrisons should be account/faction/server shared. As in, all my alliance characters on server A would share a single garrison, all my horde characters on server A would have a different one. Horde characters on server B would have a different one from horde server A. That way the decisions and choices you make in building your garrison have more meaning and weight. This would mean you wouldn't be able to have every little addon/npc or whatever on your main server/faction. It sounds like it would suck, but Isn't part of the appeal of player housing (which is what this is really) to be able to show it off? Who is going to want to come visit your garrison just for kicks? People will see your awesome place more if you have something half the server lacks, and you'll see other people's garrisons when you visit to take advantage of a feature they have that you chose against.
That's just my feelings on the garrisons. How about everyone else?
---Adding ideas that other people have come up with in the thread in this post. (and a few more of my own)---
-Having same factions alts hang out in the garrison as followers/minions. (Could even choose a character to "own" the garrison maybe?) Either way, having bank alts hanging out at shops and taverns would be pretty cool.
-Choosing garrison architecture. As mentioned, being able to choose orc vs forsaken, or dwarf vs night elf style for your garrison would be really cool, and a great way to personalize the garrison even more.
-Armor/weapon display racks to show off your favorite antique gear!
-Defend the garrison events? defend against random npc attacks.
-A new place to hang the heads of fallen raid bosses. (Yes, I do want Onyxia's head on a massive pike in my garrison!, and one day Garrosh's as well)
-Class based/flavored buildings. (mage tower, rogue den, hunter's menagerie, warlock summoning room, priest chapel, deathknight runeforge, warrior armory, druidic grove, shaman shrine, monk meditation room, paladin place-thingy)
-Flags/banners to customize. Mix or something similar to guild crests/tabbards/diablo 3 banner-flags.
-pvp suggested (personally I'm not a fan of this, and I also think it'd be ver difficult to pull off on a technical level given the personal phasing setup blizz has going)
-If it does get a defend type thing going on, there should be separate building slots for towers or other defensive structures that don't compete with the core buildings.