yeah I have a V500. there is also a V600, V700, and V750. the V700 is the one that everyone mentions but I can't really tell if it's really that much better. the V750 is like the deluxe version of the V700 that they released because it was so popular. I've looked at a lot of V700 scans and they really seem the same as the V500 in all practical reality. I'm talking about the optical resolution. there are really expensive scanners that have insanely high optical resolution like the Nikon COOLSCAN and all that. also the stations they use in photo labs are going to be really high optical resolution.
...ok I might have to write a lot here because it's kind of complex topic and it took me a while to figure this all out because nobody tells you any of this on the internet anywhere (or if you can find anything it's often conflicting and confusing information). so just bear with me, don't be frightened by all the text.
so it depends on what you're scanning right. you can scan medium format with pretty much any scanner because it's such a big negative. 35mm is a little more tricky. the scanner has to be able to scan really
fine detail. the epson flatbed scanners can scan 35mm film at an optical resolution about good enough to do an 8x10 print. that's like 2400dpi to get a 24x36mm frame to like 3200 pixels wide which will allow you to print 8x10 at 300dpi (but you could probably print it at much lower dpi and it would be fine). the V500 can do up to 6400dpi but what I'm saying is there is not much point because the resolution of the actual optics of the scanner max out a little above 2400dpi. and as far as I can tell it's the same optical resolution (or very close) on all the epson Vxxx scanners. the same goes for the image viewing size on a monitor. you can get 35mm to look good when displayed at effectively 8x10 inches on a monitor (on my monitor that's about 1000pixels wide). if you want anything bigger than that you have to move into another class of scanner and it is going to be very expensive. or shoot medium format. frankly pushing 35mm film past 8x10 is going a bit beyond the intentions of the format. that's why when you'd go to a portrait studio or for school photos even, they would use a medium format camera like a hasselblad or something.
so basically the V500 is fine for everything I'm doing. there is a V500 group on flickr if you want to see more examples of what people are able to do with it: http://www.flickr.com/groups/[email protected]/
the one thing that really sucks about it is the cheesy film holders they give you. if your film is at all cupped it can be an extreme PITA to get a good scan. there are a bunch of things people do to deal with this though. I can tell you some things I've figured out if you're interested or you can read some of the threads in the above group. one thing you should know though is, just get it out of your head right now that scanning film is a quick painless process and everything will be a lot less frustrating going into it. you have to think of it as similar to the darkroom process. you are going to have to spend time on individual images if you want them to come out the best. often just trying to get the dust off the negative is going to take a couple tries. and you''ll never get all
the dust off. just get the major stuff off and then either use the touch up brush in photoshop or just leave it for a more rustic look.