Had the misfortune of experiencing TBIT from UA935 on 12/05, with a connection on to OGG. I normally go via SFO, but 935 had 21J available with a pretty empty C cabin (upgrade cleared) while 955 didn't have anything in 17/21 open and a very full C cabin... so I thought I would risk it.
On a positive note, the first bus seemed to be on it's way pretty quickly with mostly just the F & C cabins and the immigration lines for visitors weren't too bad - in fact I'd say shorter than I normally experience at SFO.
Howver, they seemed to be full of non-English speakers and translators were being required all over. The CBP officer I saw seemed relieved to have an English speaker.
Baggage reclaim was a mess. After the advertised belt changing, anything tagged priority was very late coming out. Then customs was a real mess with a line weaving around at least 2 baggage reclaim belts.
After customs it turned out the baggage reclaim belt was broken. Loads of bags just left by the side - advice from the guy working it to people with tight connections is "you'll make it but your bags won't". My connection wasn't tight, but I didn't think I'd ever see my bags again if I left them there, so I opted to walk them over to United in T6.
All in all not a pleasant experience - which is a real shame as the 7,942 miles I travelled with United that day were otherwise some of the most pleasant flights I've experienced!