Oh can you list just a few of each?
Good:
+Jab and grab game. I'm sure you already know about his jab, but he's got the Bthrow->DA combo that gets people offstage easily, and Fthrow/Bthrow CG/infinites on some walls in certain situations. Also, Dthrow is really good at low %s for frame traps and platform reads.
+Viable and strong kill options. Bair, Uair, and Ftilt are really good kill moves and should usually be fresh enough since you have jab to refresh your moves and even if one move is good in a MU, the others will be fresh.
+Walling out options with Fair and retreating Bair. You can create a decent wall against taller/bigger enemies with full hop Fairs, and a well-spaced retreating Bair is more or less unpunishable. These let Ike control his space and force riskier approaches.
+A couple of frame traps with Nair and USmash make the task of getting kills from someone approaching the ground easier than it normally would be, though not always easy to set up.
Bad:
-Recovery. Ike's second jump is only okay, and he can take loads of damage offstage because it often turns into rock-paper-scissors with air dodges and wall of pain tactics. Aether has plenty of ways to get messed up, but most of them won't (and most of the time, shouldn't) get you killed, but that tacks on damage. Quick Draw you have to be smart about using, usually the safest way to use it is from high up, otherwise you're screwed @.@
-Has problems with camping and planking, which is part of what hurts him against Falco and Olimar. If another character sets the pace at long-range, Ike may have trouble getting in.
-Not really specific to Ike, but powershielding can wreck Ike pretty badly. The real weakness here is the very long cooldown on a majority of his moves, which is why a powershield will be so effective. As a result, you may notice Ikes don't use too many different moves (Nair, Fair, jab, Bair are really the staples), because they involve more risk. At the very least, I notice I do considerably better when my total Smash attacks are less than 5 lol. Then again, I only play MKs in bracket so...