Halo CE AR is cool, Pistol is boring.
Ok
It is cool but not actually that interesting to use. It sounds cool, looks cool, feels cool. But that's it. (Killing a player with it and then hearing them to scream at you makes it fun though. Nothing is better than annoying your opponents)
The pistol... i have never liked the pistol in Halo CE. My absolutely major issue with it is that it should not act like a rifle, it is a frigging pistol (which should be useful in games as weapons though, not just backup sidearms). Second issue is that i don't find single shot weapons interesting, unlike burst weapons, or unless they can be rapid fired like Halo 2 Carbine.
Single shot weapons are boring. Unless you give me extreme range and bullet drop, then shooting them becomes interesting.
EDIT the pistol is a semi-automatic weapon, ie single-shot weapon. Sure it has autofire in Halo CE, but the mode is kind of pointless, in campaign, where single shots against tje Grunts and Jackals are better, and against the Elites you use the noob combo. Or use grenades, much easier just to stick them with a plasma.
EDIT2, And no, playing Halo CE again doesn't feel great anymore. It is too easy, too limited sandbox, it lacks some great features from later Halos (namely hijacking, want to drive that Wraith). And its missions are too long (they get repetitive. I don't mind some long missions but usually i prefer shorter ones, and this applies to all games).