I registered for this a week ago. This morning (OK, at 00:15) TfL sent me an email telling me there would be no usage charges "today". (They sent the same email at 02.something to someone else as well.) So, let's try them tonight.
The first issue was finding them. The paper map has a cycle station near the BFI Imax by Waterloo station. It's possible it's one of the 'doesn't really exist' ones on the paper map, because we couldn't find it.
We found the ones underneath Waterloo Bridge, at the end of the National Film Theatre, between the Hayward Gallery and the National Theatre. That's probably a better location than the one for it shown on the map (at the corner of the NT) as most of it's under cover.
OK, stick in the key… amber light (checking), green light (ok!), take bike. Won't come out. It turns out that you have to really tug the things to get them out.
OK, adjust saddle height (easy), and off we go.
First impressions are that they are distinctly heavy, but as long as you're not going up a hill, they're fine. I've seen complaints that the gearing is low, but that's how it should be (you should be spinning the pedals, not straining against them).
It's interesting that the rear and front lights flash. There's an argument that flashing lights only are not street legal, and I am not convinced by flashing front lights in any case. They don't project much light – you want to stay on well lit streets at night – but are bright enough to be seen.
The bikes cope well with the cobbles between the Globe and London Bridge.
The paper map reckons the TfL journeyplanner says you can cycle London Bridge to Hyde Park in 27 minutes. Well, yes, but not on these. I docked the bike at City Hall just over the 30 minute 'free period' and it did take money off my account – there's going to be an argument with them over that tomorrow.
Something I've not spotted in the documentation or coverage: when you dock a bike at a station, you have to wait three or four minutes before it will let you take it / another one out again, in order to have two 'under 30 minute' journeys rather than one 'over 30 minutes' one.
When this happened the first time, I tried ringing the helpline. It's very quiet – too quiet for something people will be calling from London streets – and I gave up.
Other thoughts:
a) The bikes desperately need an onboard timer to tell you how long it thinks you've had it out.
b) The stations need to be much better sign posted. Actually, they need to be sign posted. You're going to get good at spotting them.
c) The paper map absolutely has to be kept up to date. Not everyone has a smartphone to look up the TfL map.
d) For the next week or so, this is your best chance to experience a bit of the attention you get riding a recumbent, because you do get asked questions when you stop. As people get used to Boris bikes, this will stop.