I bought this 3 months ago along with the complete collection of Buffy the Vampire Slayer, having little knowledge of each show beforehand and mainly going on the recommendations of friends. Buffy quickly rose to being one of my all-time favorite, not just TV shows, but viewing experiences entirely. Because I decided beforehand to watch both shows chronologically to get a full experience, I only just started this show, and am currently beginning the second season.
The show is a bit of a step-down from Buffy, at least so far. Some plot elements and the writing can irritate me, at least in the first season, but very rarely does an episode disappoint me as a whole. David Boreanz is probably the finest actor in the Buffy/Angel universe, just a step below Anthony Stewart Head and James Marsters, being able to put on many different faces and emotions seemlessly. His presence alone can make any episode worth watching.
So while I have a few more issues with this show than I do with Buffy, I definitely don't regret buying it. I did the math and found this set is the surefire way to save money, as opposed to buying the individual seasons on this or any other site/store. For a good price and hours of entertainment, this is the way to go.