Here's my take on asking others an opinion on pinball.
1) Asking others their opinion on pinball, gives me a good "long-term" look at the game's likely fun/flow/playability for me. It has value, but it's not enough information to make a purchase.
2) The ONLY way I can purchase a new pin is to get in front of it live (or play it on my Android phone with Pinball Arcade) and ask myself the following:
A) Does the theme call to me? (Am I entranced/enthralled/pleased by the theme?)
B) Do I like the flow? (Do a lot of shots seem to go nowhere, or does every shot feel like an integral part of the game?)
C) Does the artwork/sound please me?
Here's how playing a game in Pinball Arcade (a simulator on Android/iphone) led to a purchase, and the opinion of the masses, influenced me to keep the game after some initial frustration:
I knew from playing TAXI in "Pinball Arcade" on my Android that I loved the MUSIC, ART and THEME. That was enough to get Hunting for one. I bought a Taxi -- I couldn't play it for $H!T when I first bought it. I almost put it up for sale, but the fact that it's ranked ~60, told me that a lot of people enjoy this pin a lot. So I used that opinion (with a LOT of ratings), to not give up, and I learned a few new pinball skills that I needed in order to beat the game. So I didn't use opinions to purchase Taxi. Art/Music/Theme were the reason I HAD to have it. Rankings told me that for most people it's a fun game, and inspired me to not let it go, and keep working on my skills in the game.
I think fun/flow are going to be a bit more of an objective rating in the Pinside ratings. The reason I say this, is you could film a pro playing a game and you could MEASURE objectively, how often the ball is in play, and how often a a shot leads to some sort of valuable action or reaction, (versus a shot or bounce that goes nowhere). You could then demonstrate that some games have a lot of good shots, and others have a lot of dry bouncing and/or stop and go action... You could then show that there's a correlation between people's rankings of the fun/playability/flow and these results. fun/flow could be shown to be a healthy mix of objective and subjective results...
On the other hand -- art/music/theme are 100% subjective, and you can't measure that. Age/gender/country of origin, etc will all be factors in determining what themes/music you like.
Why don't I own a HS2? I played that game at the local expo, and it was BY FAR the best game at the show for me -- I ranked it a 10/10 out of the 20+ games I played.
I don't own a HS2 because car themes don't call out to me. Case Closed. I like them, but I don't HAVE to own them.
hope that helps...
-mof