That depends I suppose.
If you want him for farming dailies and such then I suppose he'd do the job as well as any other, though I personally think you'd be better off with an AoE Berserker if you have one. Edison's base attack, even with maxed Fou, is way too low for being a 4*.
If you plan to use him in harder content like high-level events, challenge quests and the like, then I'd have to say that would be difficult. I haven't used him much asides from borrowing and testing a friend's Edison as support, but he's too gimmicky for my taste.
His NP makes him a decent staller (especially with the upgrade later this year that let's him lower the enemy's ATK), and his skills make him an okay crit support. His third skill can boost someone's overcharge by two levels (very useful on the right servant like Tamamo's full party NP gauge boost) but his second skill has a cripplingly high cooldown despite its usefulness.
TL;DR Yes/Maybe for farming. No/Very iffy for harder content.
That's my opinion anyway.