The way that professions worked in Warlords of Draenor is often cited as one of the key failings of the expansion. It certainly has its problems, and I'll outline what I think those problems were, but there were some interesting ideas introduced that were actually quite cool.
Let's start out positive!
Pro: Continued Relevance of Crafted Items
I'm currently sporting ilevel 715 goggles and a 705 shield on my main character. It's really the first time since Burning Crusade that I've actually been able to continue wearing my engineering goggles late into the expansion. Admittedly, transmog softened that blow, but being able to wear plate goggles was one of two huge incentives for me to switch from Blacksmithing to Engineering back in the day (the other being the Flying Machine - both of which were added, I believe, in 2.1.)
Having items you build that can be upgraded (and in the case of weapons and non-goggle armor, that get cooler-looking as you upgrade them) to keep pace with the other sources of gear in the expansion is actually a fantastic idea. One of the problems that has always existed with crafted gear is that it all becomes basically irrelevant after you get into the first raid tier, save for those handful of armor recipes that go to blacksmiths, leatherworkers and tailors. Being able to build upgrade items for all crafted gear incentivized continued work on the professions later on.
Con: Upgrade Items Requiring a Specific Garrison Building
Though it's far less of an issue now, earlier in Warlords you were basically handicapping yourself if you didn't have a level 3 Barn in your garrison, at least on seriously-played alt (I have one on my DK - my Vice Main.) Admittedly this was maybe more a problem with Garrisons than Professions (so many of the buildings were just undeniably better than others. I love the Gnomish Gearworks, but it's never going to compare to the Dwarven Bunker's ability to outfit followers and give me a free seal every week.)
Pro: Easier Catch-Up Mechanics
In past expansions, it was always a pain to take a low-level alt and try to get them all the way up to some old expansion's level cap before you felt comfortable taking them into the next expansion's zones. Being able to start your professional work at a skill of 1, and quickly progress through recipes that granted 10 skill at a time, was a pretty good idea.
Con: Lack of Meaning to Professional Skill Level
Yeah, there's the flipside. There is a benefit to having higher skill in your profession, in that you get more of your daily resource out of each craft, starting at (as of some recent patch... was it 6.1?) 8 and going up to 20. But that just ties it to...
Con: Everything Was Based on Daily Cooldowns
Professions were so time-locked this expansion that you just cannot produce a big batch of items without spending weeks stockpiling materials. Even the professional buildings, which allowed you to produce more of those things, were still based on a "wait until it's done" system. Theoretically you could go grind mobs for Primal Spirits to make more, but the droprate on those compared with how much you could get from the Primal Trader was horrendously low. And on top of that:
Con: Crafting Materials Felt Meaningless and Valueless
Two things conspired to make going out into the world and farming totally worthless. One is that materials were readily available. As convenient as it was to have a mine in my garrison, it put me in a position when leveling up that as soon as I got to like Talador, I basically stopped bothering to actually gather any ore out in the world. Already, I could be sitting on a stack of 200 True Iron and 200 Blackrock and have nothing to do with it because my daily cooldown had been used and my Engineering Works already had a full workload, but on top of that, I had a mine in my garrison that could easily provide more ore than I would ever be able to use in a day.
Con: Creating a Problem to Fit the Solution of Garrisons:
Making Hexweave Cloth requires Gorgrond Flytrap. So when my Warlock got to Shadowmoon Valley and did his little quest to get the blueprints for the Tailor's Emporium and the Draenor Tailoring guide, he basically had to chill out and wait until he got to level 96 so that he could get his Herb Garden. Sure, he could have received stuff from an Herbalist alt or bought some on the auction house, but if the reason for this was to provide an incentive to trade with other players, why give us an Herb Garden in the first place?
Con: Alas, Poor Jewelcrafting
Blizzard's MO is that they tend to overcompensate. Didn't like sitting in Stormwind/Orgrimmar queueing for dungeons in Cataclysm? We'll make dungeons utterly unrewarding and gate Valor rewards behind weeks of rep grinds! Didn't like dailies in early Mists? No more daily quests! (This one being particularly bizarre, as while the 5.0 dailies weren't too popular, people loved the 5.1 ones and I think enjoyed the 5.2 ones.) So another aspect of this was "hate having to reforge around hit and expertise and re-gem to get around those stats as well? Well no more hit/expertise. Plus, no more reforging and you'll have an average of one gem socket at any given time!"
I'm ok with their getting rid of reforging, even if I think that the removal of hit and expertise and the elimination of haste breakpoints removed the biggest problem the feature had, but the slimming down of gem sockets has really taken the heart out of Jewelcrafting as a profession. Sure, they can create necklaces and rings that can be upgraded, but that makes the profession feel like a watered-down version of the armor-crafting professions.
The Score: Pro: 2, Con: 6
Yeah, that's a whole lot more in the "con" column than the "pro" one, and this isn't a totally definitive list (I'd include the RNG of crafted gear's secondary stats as another con, but that was a problem in Mists of Pandaria as well.)
Blizzard has said that they are putting more people to work on professions than every before, which hopefully means that they'll make it more engaging and rewarding. I will say that I applaud the experimentation done with professions this expansion - we did get a couple of really good ideas out of it - but I also hope that we see a very different version of them in Legion.