Bought a base crossover model used at 8 years old and 150k miles for a little under US$ 5k, and in two years I've put about 15k on it. It's required minimal maintenance despite being the oldest-at-purchase car I've gotten (all I've done is replaced the breaks which were worn down when I bought it), has run smoothly.
The AWD system is very good; it kept me moving safely and steadily in snowy conditions in which I saw other (presumably AWD or 4WD-equipped) SUV's struggling. Being able to switch off the AWD to save gas in good conditions is also nice; I do mostly highway driving and pretty reliably get 28-32 mpg, and my worst tank came in around 25 mpg with lots of AWD and stop-and-go driving. For reference, that's significantly better than the Impreza of the same year (the car I see it most-often compared to).
Now, the not-so-good. The car is small. There's no getting around that. If you have to haul a lot of stuff, move bulky objects, or carry lots of people, this may not be the vehicle for you. The A-pillars are a bit big and create an obnoxious blindspot but it's alleviated by portholes within the pillars. They're noticeable but pretty easy to work around if you're halfway observant.
Interior/Comfort: not exactly luxurious, but if that's a deal-breaker for you I'm not sure why you're looking at budget-friendly compacts anyway. It's reasonably-comfortable, and I've never had anyone complain about feeling overly-cramped. The climate-control system is competent enough even if it's nothing fancy. The trunk's not huge, but it is big enough to be useful, and if you've got anything bigger to move folding down the back seats for more space is pretty easy.
Performance: my vehicle is the 6-speed manual transmission, and in that configuration at least the J20B engine gives you plenty of power for whatever you might need to do on the highway or on a poorly-graded road. You can feel the road when driving this: it's a stiff, responsive ride, but not an uncomfortable one, and it's more fun than one might expect. As mentioned before, I've driven this through snowy and icy conditions that gave other SUV's some trouble with little to no slippage to show for it. The ability to lock the differential is also fantastic when you're on bad or poorly-tended roads or trails. It's not a true offroader, but my SX4 has handled some unpleasant dirt and gravel trails. In addition, this is the fourth or fifth manual transmissiom car I've driven for an extended period of time (including an Impreza of the same vintage) and this is by far the best experience I've had operating a manual. It slides into gear smoothly, and the gearshift seats securely (unlike in certain past vehicles).
Now, the elephant in the room: Suzuki exited the North American auto market most of a decade ago. They still have dealers that sell stuff like motorcycles, ATV's, and outboard motors, but they don't sell cars here anymore. I have, so far, not had any trouble finding parts (a lot of the replaceable stuff like oil filters are pretty standard), but I am also in a relatively-major metropolitan area in the Eastern United States, so that experience may not be typical. If you like this car and are thinking about getting one, ask around at your area's repair shops about part availabilty for Suzuki's before you commit. Of course, that is also why these cars tend to be available for not-a-lot-of-money.
With that said, if you're looking for an inexpensive, capable, and fun small car, I cannot recommend the SX4 highly enough.