In my experience, I've never been able to get it warmed up enough to where it feels real. Plus both caps tend to stick. Once I was afraid I'd break the case because the end cap was so tight when I was trying to remove it.
Cleanup is a bit of a pain, so that's another reason I don't use it often. You have to let the insert dry before putting it back in, and if you use a towel it will be covered in lint. Therefore you have to let it dry for a few hours. Not exactly a good idea to leave it sitting on the counter if you don't live alone. Putting it back in the case before it's dry might result in mold, which you don't want.
I have also used one of those jelly vaginas. They're a lot cheaper (around $20), but they're made of transparent silicone so it isn't tight. However, the inside is threaded like a bolt would go into it, and if you're turned on enough when you use it, it actually feels really good. Using it from the get go doesn't do much for me however. The problems with it are that it's only about 4 inches long, which doesn't allow for a long stroke length and your erection comes out the open end, and also being soft silicone, it can tear easily.
I did tear the sex in a can, which is a compact version of the fleshlight. The lip around the edge of the insert is significantly smaller so the whole insert tended to go inside the can when using it and that's how it got damaged. It's so thick around too that my hand would cramp up when using it. The actual fleshlight doesn't have this problem, since the part you hold on is thinner. I don't think the sex in a can looks very realistic either. It's supposed to look like a can of beer, but it's a pretty poor replica and nobody would be fooled if they saw it. By the way, the inserts, while similar, are not interchangeable between the sex in a can and the fleshlight.