In my opinion, Volume 2 is the best of the four sets released thus far. "Pod People" and "Cave Dwellers" are among MST3K's classic episodes, and what fan would miss out on the Shorts?
Angels Revenge: T&A are the main assets in this Charlie's Angels ripoff, wherein buxom vigilantes fight drug dealers. Notable stars include Alan "Skipper" Hale, Jim "Thurston" Backus, Pat "Mr. Haney" Buttram, and Jack Palance -- all obviously in more desperate times.
Pod People: A magical ALF wannabe from outer space visits a northern town -- wackiness ensues. "Pod People" uses the cinematic convention that aliens will attack adults and befriend children. As Dr. Forester says, "It has nothing to do with pods, nothing to do with people, and everything to do with HURTING".
Cave Dwellers: A knockoff of Conan the Barbarian, "Cave Dwellers" features a medieval world vaguely under attack. The heroine's pie pan chestplate and an inexplicable hang-gliding scene make this one a breeze for Joel and the Bots. Not as good at the Steve Reeves Hercules episodes, but still good fun.
Shorts: Arguably the best part of MST3K, the Shorts Volume 1 collects half of the bits from the Shorts VHS collection for your viewing pleasure. The shorts are a nice change of pace from the two-hour films, which can become tedious after a while if you're not in the mood for them. They also cover topics *so* obscure (from chicken farming to industrial arts to "A Date With Your Family") that you can be sure this is the only time they'll ever be on DVD.
As stated, this is my favorite MST3K volume. It may not be the best collection to pull in new fans, but for veterans of the series, it's definitely the best Rhino's released yet.