Yes they're maybe not the best movies ever written but I like them and I actually think Vin Diesel is pretty good actor when put in the right roles (riddick for example)
As far as I'm concerned fast and furious cant really go wrong, I'll buy the dvd/blu-ray without thinking about it like the others purely as they have modified cars, (usually) hot women and a plot with lots of racing/crashing/exploding things going on.
If nothing else it's better than some of the rubbish you get on tv these days....plus han's back

Mind you not sure why they stuck roman back in the series, weren't they going legit after 2fast2furious....
Tom85 - I thought the order of the films went
fast and the furious - the first one - main cast
fast and furious - Brian still a cop, ends like it does (not telling plot) - introduces han
2 fast 2 furious - Brian no longer cop and on the run, introduces romeo
(I assume) fast5 - han still with dom, romeo linked with brian etc
tokyo drift - han in japan