Borderlands - Review @ IGN

IGN has made a review, 8.8/10, of the GotY edition of Boderlands. IGN also mentions that you get all four of the expansions as well as some other stuff. The review itself is fairly long one, so here's an excerpt on how the replay value is:

There's also the question of replay value, which Gearbox took into account. After you're finished with one playthrough and have completed all the quests in the game world, you'll likely be somewhere in your mid-30s out of a total 50 character levels. The game lets you start over using the same character, bringing along all your experience, skill setups, items, unlocked inventory space -- everything but your quest progress. The good news is upon restarting the world powers up around you, meaning starting level enemies are right near your level and the items they drop are given a boost.

And here's a snip from the conclusion:

It's a thoroughly enjoyable journey that offers a steady stream of rewards that remains convenient and accessible. It's something action role-playing game fans looking for an experience more up-close and brutal than genre entries of the third-person variety should have a blast with, and one of the more memorable products of 2009.