I have a FLY-5.
I have the MadCatz version. There is a rumour that Saitek quality control went downhill once MC bought them. Reports of MC-branded X52s, 52Pros and even these would seem to substantiate the rumour...
Features are as others have explained and pretty reasonable.
I personally found the four buttons on the left of the base to be between awkward and useless, especially when you need to start altering your power distribution, like, NOW!!!!!
I found a near-closed throttle actually stops me from using the closest two, so I remapped those to the arrow keys.
Stability is absolutely fine. You should not have any tipping or tilting.
It folds up, which is good for the desktop.
You might want to put some gaffa tape over the stupid blue LEDs at the top, though. They don't flash or indicate anything and they don't illuminate the top buttons either. They just shine in your eyes whenever you pitch down!!
What irks most is the overly powerful stick springs and the adjustable bits...
The mainspring means you need a LOT of force (compared to other sticks) to move the stick from centre and this is not what you want under combat conditions requiring small corrections. You could fiddle with the sensitivity settings perhaps or the 'deadzone', but since I don't know enough about that and shouldn't have to at this price level of gaming, I don't see why I should have to [redacted] about there... Everything else works out of the box well enough.
You can lessen the main spring by putting a couple of cable ties around the spirals and compressing it down one 'turn' or so. This takes care of the sensitivity issue. However, the yaw is still quite stiff and I do find myself engaging the other axes while wrenching this thing around.
The killer is the 2-part handle. The upper slides to vary the length and is secured by a thin sprung-pin. This on a cheap stick means the two parts move and the whole stick is wonky as heck. It could conceivably be padded out to hold it in place (or flooding with a load of glue works well enough), but after a few weeks of use, the stick is wibbly as a Captain with pants on his head and pencils up his nose.
This only exacerbates the spring issue and you'll find your controls lacking the sensitivity you really need.
All in all, it's an OK starter stick for the price.
However, I *will* be getting something better once a) I have the money and b) either something better comes along or they fix the issues with the X55 Rhino, as that is an otherwise good HOTAS.