A nicely done collection. By ‘complete’ it means all those plays which are complete or complete enough to be staged in some way. No fragments. Notes of no more than a page for each play (some of them could do with more). Good little introductions to each play and an excellent general introduction in volume one.
For the most part these are good, solid translations with no theeing and thouing. The exception being Seneca, but he’s the only one whose plays can withstand that kind of thing. I used these volumes for those plays I didn’t have in a preferred translation. Especially useful for Plautus in this regard. But if it’s all you have then you’re good to go.
As to the quality of the plays, I’ll let you work that out for yourself, but if you’re pressed for time I think I’d recommend Plautus’ Haunted House, Terence’s Eunuch and Seneca’s Troades as being examples of supreme literary achievement.