If you want control, why don't cast Hypnotic Pattern? Fear? Raulothim's Psychic Lance? They all target better save.
Even Slow is better, at least it target Wis save.
Lets so a comparison to see how Hypnotic Pattern and Arcane Eruption stack up with each other.
*-Indicates this effect is superior to the other spell.
| Hypnotic Pattern | Arcane Eruption |
Level | 3* | 4 |
Range | 120 | 120 |
Components | S,M* | S,V |
Area | 30 foot cube | 20 foot burst* |
Friendly Fire | Yes | Yes |
Damage | 0 | 6d6 almost any type* |
Effect | Charmed -> Incapacitated* | Various |
Concentration | Yes | No* |
Duration | 1 minute or until take damage, action to wake | End of next round, no removal |
Save | Wis* | Con |
So to me its a mixed bag. AE has the better area, and obviously does damage (that's practically irresistable considering the number of types you can draw from). Also, no concentration is a BIG deal. However, HP is consistent (which is quite important) and the wisdom save is definately a better option.
AE works on things immune to charm which is a niche to note. I think the duration is a wash. 1 minute is obviously longer, but with AE I can still pound on the damage without waking them up.
It is worth noting that HP works in silence, which again is a useful niche to note.
So ultimately I can see niches for both. The way I see this is, if your a damage focused sorc, they you can lay on damage and get in a nice control effect, which is just solid. Also the high variety of energy types is going to be very appealing to you, as well as no-concentration. However, if your focus is on control, I think the consistency of HP (both in effect and in saving throw) will likely win you over. When your a controller you HATE randomness, you want your thing to work as consistently as possible, and HP offers the better bargain here.
I think the real question then is.... if we compare this to a 4th level fireball (aka 9d6 damage assuming fireball doesn't get nerfed...which it certainly might), is the ability to shift your energy type and throw on a variable control effect worth 3d6 damage? I think it is.