I have had a Halfway of roughly the same vintage since new (sure wish I had only paid $250 it). Mine has always made more noises and creaks than my other folders, so I just make it a point to ride it with an MP3 player, turned up. The front riser is a little bit flimsy, not quite as bad a Popsicle stick in a bowl of Jello, but if you're trying to horse a folder around by the handlebars you're doing things the wrong way anyhow.
I've experienced the dreaded "can't get replacement parts from Giant" syndrome. The proprietary front caliper brake center pivot bolt broke and Giant couldn't/wouldn't provide a replacement bolt or even a complete caliper assembly, and it's totally unlike anything any of the 10+ LBSes I visited had or had seen. The bike was out of action for a couple of years until I got around to machining a new one. You might think the monostays make changing flats/wheels easy, but guess again, the flaky brakes get in the way of everything.
I've done very few mods to it, but the brakes were so anemic I considered dual compound Kool Stop brake pads a necessity (maybe that's what caused the bolt to break, once the brakes started really working), and 50 x 406 Schwalbe Big Apples fit under the fenders (with a few tweaks) and definitely softened the ride (along with a fat-ass seat, the only one I have on any of my bikes).
So, don't construe any of the preceding to imply I don't like the bike, I love it. I'm still as fascinated by the dual monostay Mike Burrows design as when I bought it. The hydroformed Halfway name on the main tube of the vintage ones is sooo much nicer than painted graphics on the newer versions, and whats not to like about a radial spoked front wheel. I only ride mine a few times a year, but find myself really looking forward to doing so as it has a definite personality, which is so lacking in plain vanilla bikes. It attracts attention from gear heads and other interesting people, not so much from jerks. I wouldn't recommend it as a reliable everyday commuter, but it might serve well for your occasional use plan. You could do a heck of a lot worse.