DeepT had this to say on professions:

After doing all the professions to a reasonable level (not including specialist blacksmithing), I have decided none of them are that good.

Alchmey:
None of the potions give fantastic buffs or effects. Powerful, usefull effects are very short lived. For example one potion gives 1000ac, but for a mere minute. Another gives invisibility, for a mere 30 seconds. And then healing potions have timers which is stupid. I can understand the 'diablo' effect being worrysome, however there seems to be one key factor blizzard missed. In diablo you can buy an infinite supply of potions, in WoW you can not. If they removed timers people would got nuts for a short while and then suddenly the supply would dry up. Healing potion prices would go through the roof. Still maybe you might suck down 3 or 4 potions in a fight, but then you would have to ask yourself, was spending 1gp in potions worth killing 1 mob? You want a money sink? Remove those timers.

Tailoring / Leather working / Smithing: At low levels this is great, but the problem is player made items quickly cease being usefull compared to common 'green' drops. While there are a few specialty items that have very nice benifits, the vast majority of this stuff is crap. I thought all crafting was supposed to be slightly better then common quest rewards and worse then speical quest rewards. Blizzard really needs to buff these professions to bring them up to the level they need to be.

Engineering:

Explosives -- These are garbage. They do no scale up enough to be useful and are not worth thier cost. The top bomb does like 450 pts of damage. It costs materials worth a few gold in the AH. My spells I can cast for FREE can double that damage easily, the better ones can do 1000s in a much larger AOE. My theory on a bomb is that each level of bombs (geared toward a certain character level) should do like 50% or MORE of a mobs health, maybe even 75%. Remeber this is a large economic cost to using the better bombs.

Bots -- Actually quite usefull for a few levels and somewhat expensive. I would only add more bots for granulairty.

Trinkets -- Mostly worthless. The unreliability factor is way to high. Net-o-matic is far overrated. Its rare to not miss or miss-fire. In PvP maybe 1 out of 5 times I use it, it has desirable results. They need to remove or tone way way down the misfire probability.

Gadgets -- normally they replace some armor piece such as belt, helm, boots, etc... rarely, if ever, are any of these better then what you would have to replace them with. For example, do you want to wear your +10 int / Stamina boots that give you +6 shadow damage or gnomish rocket boots that let your run fast for 20 seconds, have a 15 minute cooldown, and a 45% chance of simply exploding instead of working? Further worsening the fact is that you can not change armor in combat, so if you need a quick getaway you just cant hot key them on and run for the hills.

Overall I am dissapointed in the quality of crafted items in the game. With the exception of engineering which has just a very very few useful items (Green Lense, Shrink ray, Death Ray) I would just make a gatherer. Herbs/Skinner or Mining/Skinner and then just buy the good shit from the AH.