I'd really like to know how many people have bothered to purchase the Master Riding skill since it became available from the trainer - or rather, how many of those that could afford to buy it have bothered, because most likely there is still a fair chunk of the player base that doesn't have enough spare cash lying around to get it either way.
I'm a bit torn about it myself. I have enough money to buy it for all of my level eighties if I wanted to, but I'm not sure whether it's actually worth it. I've just never seen another riding skill that does so little while costing so much.
I still remember buying my first ever land mount back in Vanilla, at level forty. I had to borrow a couple of gold from a friend because I didn't have enough money, but boy, was it ever worth it. Up until then I had trudged up and down the whole length of Stranglethorn Vale on foot so many times; it was awful. Being able to speed up my progress by sixty percent all of a sudden felt amazing. These days basic riding is much cheaper and you can get it at level twenty, but if you've ever levelled in the Barrens you'll still appreciate the difference it makes.
Then came epic riding on land. Again, I first got this in Vanilla back when it was still expensive and required you to save up for quite a while. But again, it was so worth it. The first time I rode my Swift Stormsaber around Darnassus, I kept running into pillars and walls everywhere because OMG it was going so fast that I couldn't steer properly (or at least that's how it felt at first). Again this experience has been downgraded somewhat since then, since the ultimate goal is now to be able to fly, but it's still noticeable that your mount goes considerably faster after you upgrade.
When I first bought the basic flying skill in Outland, I actually ended up having second thoughts about it shortly afterwards. This was back when basic fliers only went at the same speed as normal ground mounts, so I got onto my gryphon in Blade's Edge (where I had hit seventy for the first time), flew around a bit... and then went back to my land mount to continue my questing, because the flier was so much slower. Still, at least it meant that I could get to certain places that were only accessible by flying if I wanted to. Plus, Blizzard has fixed the speed issue since then so even normal flight goes faster than your ground mount at least.
Epic flying... oh yeah. I couldn't afford this for quite a while either, but after I watched a friend who had it zoom around Terokkar Forest I was so amazed by the sheer speed of it that I decided that I had to have it too and started saving up. Best flying skill ever - I always make sure that my alts can get it as soon as they hit seventy these days.
But this new flying skill... it costs as much as epic flying but only increases your flight speed by ten percent or something, relatively speaking. My priest got it automatically from her rusted protodrake, but I can't say that it feels like she's flying any faster than my alts. I suppose it would be noticeable if I was in a straight race with someone who has the upgraded skill, but when does that ever happen?
I guess I'll wait until Cataclysm to see whether there's anything else that's new and expensive that I'd rather spend my gold on, but I'm curious how other people have approached this.