As I said in my review for the DC Comics Presents collection, my favorite comics as a kid were the team up ones. Marvel Team Up seems to hold up a lot better than its contemporaries. In the days before there were crossovers in every other issue, this was the place to see Spider-Man interact with the rest of the Marvel universe on a regular basis.
As unfathomable as it may sound to today's comic fans, back in 1972, Spider-Man was only in one comic a month. Marvel Team Up was the test to see if Spider-Man could support more than one book. Did it work? Peter Parker, the Spectacular Spider-Man was launched during this book's run and Marvel Team-Up was eventually canceled so they could put out Web of Spiderman, a third monthly. While things have changed a lot since MTU ended its run in 1985, last I check, Spider-man was coming out every three weeks.
Back to business at hand. The thing that stands out most in my mind about this collection of early Marvel Team Ups was the friendship between Spider-Man and the Human Torch. While it existed before this volume, this is where I believe it was cemented. Spidey and the Torch team up four times in the first twenty five issues. Not only that, Marvel apparently had enough confidence in the Human Torch as a solo character at one point to have him be the lead character six times in MTU's run.
Aside from the Torch, Spidey teamed with a host of guests, like the X-Men before they were popular, The Vision, Captain Marvel, the Thing, Thor, The Cat, Iron Man, Werewolf by Night, Namor, Captain America, Ghost Rider, the list goes on and on. Some of the stories felt like they were just an excuse for Spidey to interact with other heroes but others hold up fairly well for pre-1980's stories. At the Essentials price, it's a lot of super hero action.