I've built a few full sized Virtual Pinball cabinets using Visual Pinball before for myself and some friends. Here is a video I shot of my first cabinet I built back in 2010-2011 playing Congo.
I traded it to another member who still to this day is enjoying it. He liked it so much that I joked about building him a portable and he asked if I was serious and would build it for him. So I said sure as long as I don't have a hard timeline and a flexible budget. The full build thread can be seen here for those interested in seeing it:
http://www.maaca.org/viewtopic.php?f=25&t=8110
After I traded away first virtual pinball away I sort of missed it and decided to make another one except using a Pinball 2000 cabinet. I have always thought this cabinet form factor was perfect for virtual pinball and I had a third LCD mounted to reflect the DMD onto the playfield glass. It is perfect because it allows you to still be able to see what going on the DMD without having to take your eyes off the action.
The partial build thread can be seen here:
http://www.maaca.org/viewtopic.php?f=25&t=6890
I had it pretty much completed and just had a few little things to tidy and wire up in regards to force feedback hardware such as Siemens contacters that would go "thump" whenever you hit the flippers, slings, pops or replay knocker. There were also Cree RGB lighting that would also go off with the game during certain modes or shots as you can sort of see in my Congo gameplay video above. That was in its early stages of development using an LEDWiz to interact and make it "feel" and "sound" more like you are playing a real pinball. I know there is nothing you can really do to make virtual pinball feel "real" or change the way it plays but it does "enhance" the experience a bit.
The main problem I found with Visual Pinball is the quality and feel of each table is very different and based on the table author's style, artistic skills and game accuracy. I worked with a well known and popular table author back in the day named jpsalas on a few of his recreations such as Congo because I could take pictures to send to him and beta test his table before he releases it to the public. Before I talked to him I enjoyed all his previous recreations over the years such as Flintstones and Indianpolis 500. I actually bought both those pins in real life basing it off only playing the digital versions. What surprised me when I started talking to jpsalas at first about Congo was when he creates all these tables he has never ever played the real thing before. He just looks at pictures from ipdb and youtube game play videos. I was pretty amazed at how accurate he was able to replicate the game without ever playing it. Anyways, I believe he is retired now but there was a great period of time where he was turning out a new table every other week. You can see all his past recreations here:
http://sofie40.no/jpsalas/
There were some other notable table authors too such as unclewilly, DAZZ, destruk and one guy named Tipto who did an amazing recreation of T2 "Chrome Edition". It took a year to complete and the teaser screen shots he posted were unreal. Everyone was very skeptical because the usual trade off for image quality would be table performance meaning the ball would be laggy or choppy during game play. But it played very fast and smooth while at the same time looking very realistic too.
Also wanted to comment that those who are basing their opinion off Pinball Arcade on your mobile phone or consoles is not the same as playing it on a full sized cab. On Pinball Arcade you don't get a full view of the playfield at all times or if you do it is very small otherwise the camera view constantly scrolls in and out. With a full sized virtual pinball cabinet you get a static full view of the playfield like you would playing a real pinball.
It's too bad by the time this table was completed my interest for virtual pinball was pretty much done. There was a period of time I thought I had everything I wanted in my little game room. I had completed my full sized PinMAME cabinet, childhood grail Street Fighter II Champion Edition cabinet which I MAME'd, Fabi foosball table and 4' x 8' pool table. Boy did that all change after I got my first real pinball and over the years everything I said I would never get rid such as my beloved pool table I did!
Here is a recent walk through of my gameroom (that's spiroagnew playing Roadshow there)
You will also notice my P2K virtual pinball is not there either and I sold it in favor of squeezing in White Water. I figure I haven't really had any motivation or desire to play or work on it since June 2012. I had a friend who was interested in one so I basically finished it up and sold it to him for exactly what I had into it and it's being played a lot. Now part of the reason why I had lost interest was mostly because I was more into real pins but prior to this I have been playing with virtual pinball since 2009. I am not sure where you friend is located but if he close by to me I could help him setup the software and he could make a temporary setup like this and play with the keyboard for now. He could get an idea of ball movement and physics of playing a virtual pinball. I also wouldn't recommend buying that UltraPin that is or was in the Starburst showroom because it is sooooooo over priced for what you get or don't get.
I think the deciding factor in the end will be does your friend have the space for more then one pin? I don't know if I would be in the hobby if I only had room for one pin because it could get old fast. That's why you see that usually after people get pin #1 that #2, #3 and #4 are not long to follow after. I've had a hand in helping a handful of people over the years who start out by saying all they want is one pin but end up with a collection. Another factor your friend has to consider is how much pins are going for these days.
If you have any questions feel free to ask or shoot me a PM.