Nah, it's cool. Just compare to Web, which is the same level and does almost the same thing and...
Wait, why are you laughing?
Web has some advantages. Visions takes a minnor action to sustain and a minor action to repeat the attack while Web is a fire and forget daily. PLus Web produces difficult terrain.
Whic is not to say that I wouldn't usually still rather have Visions, only that there are certain situations, most obviously when you have something else to sustain, when Web is a better bet.
A great power, and actually not hard to thwart for a DM either.
Step 1) Get a monster beside the wizard.
Step 2) No really, that's about it.
The wizard has to spend two actions to use it, one of which triggers an OA from the monster. The third action either has to get the wizard away from the monster, or is an attack, which also is a time OA can be used.
Hardly, once you've cast the spell the minor to sustain doesn't trigger anything, and the attack is a close burst so doesn't provoke an OA.
I can play the experience card here having used Visions of Averice for the first time earlier this week. I'd say that there are a lot of variables involved, including the following:
Mix of monsters - melee vs ranged: Against ranged monsters the power is initially of limited use, but imobilising artillary allows you own melee types to get in close and pin them down without having to worry about the monsters shifting back and continuing to attack using ranged powers. Against melee monsters the situation is largely reversed in that you can initially take them out of the fight but sooner or later you are going to have to wade in and fight them. Flanking is much easier against an imobile foe, of course.
Mix of party - following on from a monster mix, the party mix is also significant. A mele heavy party won't gain any major advantage against melee monsters other than slightly better flanking potential, but could close down troublesome ranged monsters. Conversely, a ranged heavy party with find melee monsters easy to manage but gain nothing against artillary.
Overall, assuming a balanced party with a mix of melee and range and a similar mix of monsters, what Visions is really going to achieve is to let the party send the most effective members against the best choice of monsters (melee pinning aartillary and ranged attacking melee monsters) with greater ease. It's useful but not always major, especially given the luck of the dice.
Terrain is the other major factor. Dumping Visions in the middle of dangerous terrain can result in a lot of extra damage. Casting the spell on a fighter who is using Rain of Steel is also quite amusing. I'm also sure it's not entirely a coincidence that Visions essentially takes two minor actions to keep a bunch of monsters pinned in a burst 1 radius while still leaving the wizard, often with a burst 1 at-will attack with a standard action to use that attack.
In the whole, though, I think that Stinking Clound is likely to be more effective in at least as many situations.