I collected loads of these guys. If you're looking for a review, pretty much everyone here is spot on with their reviews.
Lots of the Covenant figures aren't really much to look into unless you like the sculpt. The Brute, Grunt, and Prophet figures are glorified statues with some basic arm articulation and head swivel. Good sculpts, but as toys they're lacking.
The Jackal and Drone figures are a little bit better, but they're pretty unstable without their stand.
Elites are the best Covenant figures, but they suffer from small feet. The Arbiter figure is basically the only one who has reasonable feet and can stand reliably on his own. Their articulation is decent, but still nothing to write home about.
The Spartans can be split between Halo:CE and Halo 2 Spartans. Halo:CE dudes have stiff joints, and I was always paranoid about snapping them. They also don't have the best articulation, with next to no hip or torso movement. The Halo 2 Spartans are really great and solid figures, and I think the only thing holding them back now is the fact that these are almost 20 years old. If you like Spartans, I'd recommend picking up one or two for your collection.
There are a few odds and ends like some marine variants and vehicles, but I wouldn't worry too much about those. The Halo:CE marines have like 5 POA, and the ODST is a bit too rare to pick up unless you're collecting the set. The vehicles and their mini figures are fun, but they obviously don't scale with anything except each other.
