Summary: I'm enjoying the bike immensely and I have had no mechanical issues. A few minor items were quickly replaced by excellent customer service by both Tern corporate and ThorUSA (the dealer from which I purchased). It's suiting me well for my daily bike+train commute in the Philadelphia area.
I have commuted almost daily on my 'new' Tern P7i since late July 2012. I have done 117 commutes (8.5 miles
round trip plus two 25 minute Amtrak rides daily). This includes folding and unfolding the bike three times (Train, Office, Train).
So that's about 350 folds.I have one very steep downhill in the morning; I hit 35 MPH and then have to brake at the bottom for a one lane railroad underpass. In the afternoon that same hill is a 315 ft vertical gain in about 1/2 mile -- grade is 7-9% with a short section at 18%.
The built in front light is great. It's not quite bright enough for the midwinter dark morning commutes (I use an extra Fenix 180 lumen flashlight was well), but for most of the time it's nothing to switch it on even on just 'gray' days, so I'd presume I'm safer than when I went without a light unless it was dark.
The Shimano 7 hub has very different gearing and feeling from the SA 8W on my previous bikes -- there is no "direct drive" gear and in gear 1 it is definitely harder going up the steepest hill. But I love the fact that I can shift while pedaling and I haven't even had to adjust it even once in 1000 miles / 7 months.
The stock front brake pad was soft and wore out quickly -- 500 miles. I replaced it with Kool Stop dual compound.
The warranty items I have had replaced were:
1 - the Magnetix plate fell off the bike during the second or third ride; due to undertightened nuts from the factory.
2 - I couldn't get the "FreeDrive" chain cover to stay on, after partially removing it for a flat tire change. Tern kindly sent me a new one.
3 - the plastic handlebar grip "T Tool" insert cracked and wasn't holding the tool securely. for items 1 and 3 ThorUSA sent me a new one quickly.
My previous two bikes (Downtube IXNS and 8H) lasted about 3500 and 3800 miles respectively before the frame broke near the seatpost (same failure both times).
I am hoping and expecting that due to the design and construction of the Tern that I can get at least 4 years / 6000 miles plus out of it!