No. They are OK with a blitz very early, and might knock out one or two people right away, but then they are done. Indeed, I would put them in the bottom half of all the stock races.

When they develop worlds, they don't design them to support strong populations. They focus on splitting their tiles between factories and labs, and they often lead to money problems.

Worse, their super ability quickly turns into a weakness. It gives them a large military rating, but their military is actually weak. This means they will happily get into wars that they can't actually win.

Worse, even when they build ships with better engines, they put them in fleets with Super Dominator Corvettes. This means that their attack waves get slower and slower the more space they have to cross. You can easily pick off their few strong ships which do not make the most of their strength, because they mix fleets with strong ships and the garbage free corvettes. This lowers the attack strength of each fleet they field significantly, making tactical wars against them a breeze.

I rarely concider the Drengin a major threat. I'm usually more concerded about the Korath with their spore ships.