If you are looking to buy a VAIS unit, make sure you can truly live with the design quirks mentioned here on the board before buying one.
I have had mine since August. I bought it eyes open after reading the reviews here from those who already had installed one. I agree, the sound quality is excellent. The rest of the software was very inconsistent and you really had to work hard to get playlists to play correctly.
I noticed a month or so ago that someone had upgraded their software and it worked much better. I contacted VAIS and they said the version I had (3.42) was "very old" and to return it to be reprogrammed. So, off I went to the garage in the cold Chicago winter to de-install the unit. By the way, you have to remove even the head unit cables when you take the VAIS unit out so the entire audio unit has to come out each time.
I sent it in and recieved it back about 10 days later with software version 3.52 on it. I installed it but it suddenly would not work with my iPod! I tried it with my sons iPod and it worked. I wrote to VAIS and it seems that now they can program it in two communications speeds, slow and fast. They sent it back to me in the fast mode which doesn't work with my 3G iPod. Now my only remedy is to take my 400h apart (again) and wait another week or so for them to reprogram it or buy a new iPod. Why on earth they didn't call or write to ask before assuming is beyond me.
Because I have to use it in the AUX mode for now while I contemplate the next move I can't tell you if the software is any better.