I haven't used Agent in years, but I know it is a very robust news reader, ETC. I know the users are very loyal, and a bit zealous about guarding it as the premier news reader.
As TG mentioned, Agent don't do yEnc. yEnc is a new method of encoding binaries when someone uploads them to a news server. It reduces the overall size of the upload, thus saving time to up and download them. Many Agent users have been fighting the change from UUEncode to yEnc simply because their reader doesn't support it yet. (I understand it will in a few weeks. Thats when Agent users will hail the new yEnc standard as the second coming of Christ).
Usenet is kind of the "Wild West" of the internet. It is a land where opinions are like Ay-holes and the laws of good behavior and decency do not apply. Thats why I avoid most discussions on all Binaries newsgroups, and thus don't need a reader like Agent. I prefer NewsBin, which is a no-nonsense leech application for binaries, binaries, binaries.
As for a premium news service, I have used Easynews, Airnews, and one other one (I don't want to give the third one any free advertising, they crapped on me) and for my current situation, Airnews is the best.
Unlimited downloads at 256k. For anyone with a low-end DSL connect (like me, unfortunately) or 56k, this would be the way to go @ ~19.00.
If you miss MarzAttacks, he is still active at Alt.Binaries.Warez.Amiga.
By the way- Thats where I first met TG. *Salute*