Great car overall, had 0 issues, but then again it's a new car (1 year only), so that's to be expected.
Engine is good (I have the 1.4 petrol manual), wouldn't say it's the top of the class, but does the job and it's very silent. Reviewers tend to say you need to rev it a lot, but that's just not true. If you're in the correct gear, you can feel the pull from just over 1.5k rpm.
Gearbox feels solid and smooth, but 2nd gear can feel notchy when cold or when you rush shifting gears. And that takes me to the only complaint I have with it - that the gearshifts feel long, so if you're shifting quickly, you really need to 'abuse' it a bit.
Suspensions are soft, way softer than on a Golf, so very good cruising car.
I like the exterior as well, but you should know that the interior is pretty boring, but very functional. Visibility in the back can be shit though, I adjusted my seat for max rear visibility, but other might not be willing to do that...it's a coupe style car so, yeah.
For the money, was definitely worth and beyond...not sure how expensive the i30 is in Switzerland.