I got my first bull pup last month, a PS90 tri-rail. I mounted a Leupold AR 1.5-4 x 20 scope and a TLR1-HP weapon light on it.
What a fantastic close quarters battle rifle this makes. The light has a very tight focus and can be used like a laser sight at close range. The rifle is very easily handled and shoots like a dream. I have no problem maintaining a 3" group at 100 yards with SS195 ammo. This is more than good enough for any realistic purpose.
I also picked up the Elite Survival System discrete case and it is very well designed, specific for the PS90. I bought an airsoft double mag molle carrier and it is OK (nothing special, but it is cheap and works).
Once I had tested it for proper functioning, I converted my 30 round mags to 49 round capacity (takes a hack saw and a wood rasp plus 5 minutes of my time).
I have two more accessories to get. I need a sling and highly desire a brass catcher (FN designed a cute one that mounts directly to the gun).
The more I handle and use the PS90 the more impressed I am by it and by how well engineered it is. The trigger pull is a bit heavier than I would like, but otherwise is not objectionable. Recoil is nothing to speak of.
The safety is pretty rudimentary (blocks trigger only) so as far as I am concerned this gun only gets a chambered round when I am ready to shoot. My AR15 and FAL are the same way which is why Condition 1 (cocked and locked) is not even vaguely attractive to me with any of them.
I am strongly considering doing a Form 1 short barrel conversion on it if I can find a P90 replacement barrel for it (the chrome lined barrel is not optimal for aftermarket cutting). The 5.7 x 28 mm round is designed for the shorter barrel so you aren't giving up that much velocity returning to the standard P90 barrel length.
In case you can't tell I am pretty smitten with this particular bull-pup. Doesn't hurt that it has the Star-Gate thing going for it either. I see why they picked it for SG1 standard issue.
P.S. These are all web pics, I can't find my stinking camera (just used it Saturday).