With the same RMB (rack mountd battery) as the Meerkat and Trails AL the reviews and comments on those should be largely relevant to these.
Pro's:
Dirt cheap. Good to start off with to see what you like.
If you take it into town or to the pub you'll not be too concerned it may get stolen.
Replacement batteries are available from £40 if you fit them inside the case yourself. New battery+ case about £150. Should be replace about once in every 8-12 months.
Nice for short commutes (4 to 6 miles).
Can mount a second battery, extending the range.
So cheap that you can just by 2 and hardly ever suffer downtime (even a reliable expensive bike may have long times waiting for parts etc.).
Cons:
Heavy. Heavy batteries.
Cheapo chinese parts. Won't last forever.
Unlike the meerkat this one has no disc-brakes. Expect having to replace them a lot.
New LiFePo4 batteries are available in the USA $399 for 6.5Ah is mighty steep.
Not a very sophisticated bike but a good price - I paid nearly that 4-5 years ago just for the Currie kit - I found it great for zipping around town (I had a 2 mile commute at the time) - it only lasted me a bit over a year but I felt I got my money's worth in fun at the time. I kinda miss the noise the chain drive made - it was a good sound track for darting around town.
The Zip kits (rear-wheel, rack, battery, etc.) are on ebay now for £150.
For that price they are great fun, and about the same as what one pays for just a battery.
Oh, right - maybe mine wasn't so expensive - it's been a while now - mine was a Currie Electrodrive from eBay - I assumed the Izip was pretty much the same.