A few thoughts:
1) Personally, I love my Polaroid 360. I refurbished the flash but never use it anymore. FP-3000B is sensitive enough that I can shoot almost anywhere in natural light. If you want to use a 3rd party flash, get a Polaroid 350. The camera is very rugged and has been dropped, swung around, packed in unprotected bags for about 4 years now. Since I have a spare, and they are cheap, I don't treat mine with kid gloves. Still, it holds up well.
2) The lens of the 350/360 is glass and is nice quality. There are portrait and close-up kits available which are +1 and +2 diopters with matching viewfinder adapters. Also, available is an orange cloud filter that fits over the electronic eye and the lens to add contrast to B&W shots. Regarding the lens...the print is 3x4....all that talk about lp/mm and stuff is bogus on this format. I scan my prints and enlarge to 8x10 with excellent results. This film is large and not made to enlarge beyond 3x...because of that, the lens details are less relevant. The enlargement limitation is the film, not the lens.
3) Sometimes you needs to press down on the pressure plate a bit and deform it so that it will accept the thicker Fuji film packs. Once this is done, you don't need to do it again. You can still use Polaroid film with the camera (if you can find it ;-). Pressing on the spring doesn't break anything.
4) I shoot a lot of street photography with my 360. I find it creates an interesting social dynamic that leads to more photographic opportunities. I often gift the print and bring home the negative to scan. It appears much less confrontational than an SLR. The exposure latitude of the film is pretty narrow. With the negative side of it, there is more leeway. Still, the electronic eye and auto-exposure are very helpful. Otherwise, you'll need a light meter or a very good eye. The 180 camera has a faster lens which allows for more narrow DoF. That can be useful. But, it is fully manual. That might work for static shots but not for street IMHO.
5) I have refurbished many 360's and find that the electronic eye tends to drift...sometimes on all settings...sometimes on specific ones (say ISO 75 Sunny). Sometimes the drift is beyond the L/D controls available on the camera. You can get a slotted o-ring at the hardware store which slides perfectly over the electronic eye. Glue a 1-2 stop ND filter on it (depending on what the camera needs). Then you can pop it on or off depending on the situation. Very convenient and very durable.
6) You can use inexpensive CR123 batteries by using a rubber band to squeeze the battery holder shut. Like in this photo:
http://www.flickr.com/photos/amuderick/675332442/
To sum it up: The camera will cost you the equivalent of two packs of film. It is solid and high quality. You can't go wrong for the price. All of the pack film shots on my Flickr stream (link above) are taken with my 360.