I mentioned, previously, that the new version of Jetpack Joyride has a feature called gadgets. I've now had a little time to play with them, and have a few thoughts.
Air Barrys: I like these. When you touch the screen while walking, you jump into the air very quickly, high enough to jump over any obstacle (I think). They're fantastic for any mission involving high fives or walking. They're probably also awesome for 'go Xm without using the machine-gun jetpack', if you only have that jetpack, although I haven't tried that.
Nerd Repellant: Graphically amusing (all scientists disappear, flashing lights are turned off, and tumbleweeds blow across the bottom of the screen), but useless. Annoying that this seems to be the only gadget required by a mission.
Insta-ball: Meh. Get a bit more distance. Think I've only used this one once.
Gravity Belt: Would seem the converse of the Air Barrys, but I find them really annoying. The changing physics (falling faster) makes the whole game play differently, so they hurt more than help. Annoying side effect: you can knock over scientists by falling, forcing failure on 'go X distance without harming scientists' missions.
Missile Jammer: Looks like it makes a certain percentage of missiles fail. Seems pretty useless, but this is the only one I haven't played with at all.
Token Gift: Get a free Token at the start of the game. Nice, useful. I use it on most missions that require finding a certain number of tokens (or certain number of spin wins).
Freeze-o-matic: Meh. Get fair bit of extra distance the first time you hit the deck. Would strongly contemplate using them if they worked more than once (after a blast or after dying from a second chance).
X-Ray Specs: Visually cool, but mostly useless. Only real use I can see is if you need a certain vehicle for a mission, but are mostly focused on another mission that's hurt by having a vehicle (such as X high fives). Even then, I think they're pretty iffy.
Gemology: Small percentage of coins are turned into gems, which are worth more (although I haven't yet worked out how much more; I've forgotten how big most of the coin groups are, making it difficult to calculate). Generally useful.
Ezy-dodge Missiles: Missiles move much more slowly. I think there might also be a side effect of a larger proximity for near-missile calculation, but that's totally a guess. I use them occasionally for near-missile missions, but am not thrilled with them.
Magnetic Tokens: Tokens are attracted to you, and thus, much easier to get. They're less likely to kill you, so it's a generally useful gadget, but I think less useful than many others. I've used this only a few times.
Flying Pig: A piggy bank, at random intervals (which can be close to zero; I've seen two on the screen at once a couple of times) appears, scattering coins. If you run into it (or it gets plowed by a missile, which is awesome), it drops a load of coins. I use it occasionally, generally in tandem with the coin magnet.
Free Ride: Start the game (unless you "won" a head start the previous game, in which case it appears as soon as your head start wears off) in a vehicle. Allows the 'Another Way In' Achievement (I think only if you start with the teleporter, although I haven't paid close enough attention to be positive about that). Doesn't allow you to use a bought head start. This is one that I use all the time.
Coin Magnet: Just like a magnetic vehicle, except without the vehicle, and not as strong. Very generally useful. This is my 'go to' option when I don't need anything specific.
Lucky Last: You win on your final 'final chance' spin. I'd like this better if it were possible to have it happen more than once (ie: if the final spin is a blast that hits another token, or gives a second chance that yields one or more tokens). As it is, I only use it when I have a mission based on number of times winning final spin. Even then, I think it's rather iffy.
Flash: A dog runs along the floor, knocking over scientists and picking up coins (sometimes jumping for them). Cool to watch, but not especially useful.
Dezapinator: Has a small chance (one in ten, maybe? Maybe even less) of disabling any zapper. This is another generally useful one that I use fairly often when I don't have two other, specific needs (or have a mission like 'fly over X zappers'; if they're disabled, flying over doesn't count).
Turbo Boost: Every so often (once every 1500m or so, I think) a little machine will fly out from behind you, and leave three rings in the air in front of you. These rings will blow up missiles, disable zappers, and make you go faster for a bit. I like this one, but it does make a bad distraction sometimes. Mostly gets up-marks, though.
That's all of them, and they're enabled in groups of three. The first group is immediately available, and each other group is enabled, in order, when you buy two more gadgets. So you need to buy ten before the last three are available.
I go back and forth over whether I like them or not. Choosing them is strategically interesting, but almost all of them change the way you play. They do have interesting effects, though, and go a long ways towards making some missions easier (or harder, come to that).