Pros:
The fuzzy little guys come with an obliterator type weapon choice. As the round demands, they can break out a lascannon, heavy flamer or multimelta. This makes them a great situational support troop.
The hirsute fellows are henchmen, so they can be made troops by including corteaz. Mixed in with other henchmen can give you some intersting combos and make for some good fire support.
The wooly little dudes give their unit a buff. One of the options (if you roll it) is to bestow rending on the weapons of the squad. Rending plasma guns or flamers anyone? Another gives a 12" range boost. 36" multimeltas? Yes, please!
Cons:
Even though they are like them - an obliterator these fuzzbuckets are not. They do not have the luxury to be able to move and fire with the exception of the heavy flamer only. This means you will usually want your jokaero parked some where.
The gorilla guys are bad at shooting. We're talking a bs of 3 here. Reliability is not good. You'd need to take them in numbers to get reliable hits.
The upgrades table is a disaster or an argument waiting to happen, for the hairballs. For each jokaero you field you will add one to the diceroll to determine the upgrade bump for their unit. If you roll a 6 or more you get to roll twice on the table.... But you have to add to your totals the number of jokaero in the unit above one. This can mean you could possibly only roll 6 or more if you have a lot of jokaero. It also means you miss out on some of the lower numbered upgrades. Until a FAQ comes put this is a major pain.
The Apes are pretty slick but two of the upgrades are pretty bogus. For competitive play you usually dont want random things in your army. You want consistency. Theres a reason people dont used possessed chaos marines.
Space Monkeys are squishy. Were talking guardsman type numbers here. If your going to field them youll need to keep them safe, and that means a transport is mandatory.
Finally, it takes a lot of bananas to keep the chimps fighting for you. Clocking in at 35 points each you will need to make the most of them. This is nearly the price of a wraithguard!
Assessment:
I wont be fielding them except in very rare places. I could see dropping one in a unit of servitors or plasma henchmen for a shot at a super guns upgrade. But for me the cons make fielding them in any larger numbers a non possibility. Remember that in GK you can get more than three multimeltas for 35 points.
So what are you all thinking? Are they something you wont leave home without? Or are you passing on them?