Also have the UE350vis since early October last year and they work great.
Definitely recommend getting Comply tips... preferably the ones with the earwax filter. (Note to self: get the filtered tips next time. Wax buildup is nasty.) All silicone in-ear tips never fit my ears, and the ones that came with the UE350vi are no exception. The carrying case is also unwieldy to use - I opted for a felt carrying bag to store my headphones for daily use.
Sound isolation is great too. Highly recommended for transit users in cities as you can still hear your music at comfortable volume levels on loud trains and buses.
The inline control isn't great to be honest. Volume controls work but the middle button frequently has trouble distinguishing between play/pause and next/previous track. Nowadays I only use the volume control and leave transport controls up to my Pebble. The microphone is actually worse than the stock Apple earbuds - you need to hold it up to your mouth for the other party to hear you clearly.
And as for the sound itself... I would suggest using the Acoustic EQ preset on iOS devices. It's a good balance of bass and treble. Don't use Bass Boost as it turns the sound into a muddy mess.
Glad to hear Logitech support is as good as always