I have owned both the mag-stick, and currently own a pair of u360's.. hands down the mag stick is terrible, and the u360 rocks.
Well I wouldn't say it's terrible. To each's own.
I've been using mag stick plus' for a little while now and with a bit of adjustments you can get it to feel decent enough to merit using them. The best thing about them obviously is the top-switchable 4-way/8-way functions, but when in 8-way you have to get used to the diagonals because it's harder to hit them.
The reason I went with the Mag-stik is because I wanted to have a physically restricted 4-way joystick, and still have an 8-way. My control panel doesn't have a lot of space to fit multiple joys, so having a stick that does physically adheres to both is an ok choice. You don't get the top-switchable physical restricting 4-way action on the U360's.
I ended up swapping out the microswitches from the stock SAIA ones to some OMRON switches. The feel is so much better, because the switches that ship with them are way too frigid. CHERRY switches are way too soft for the Mag-stick, OMRON's seem to be a good middle ground between the stock SAIA & CHERRY microswitches.
Also, you should know that the Mag-sticks have a short throw, so if you're used to the Large-throw of North American cabinets (via Happs Comp, or EuroSticks) you'll be frustrated with the feeling of the Mag-stick.
I wish the Ultimarc guys would do another version of the Mag-stick but with better 8-way action, or even better a large throw on 'em.
If you know anyone that has the mag-stik, I'd recommend trying them out before you buy them. But if you don't , then gather as much info as you can off these boards. A lot of people seem to favour other joys rather than the Mag Stick, but I say if you can adjust them to your liking, you can go the distance with them.