I actually own 2. They briefly went on sale here in the U.S. earlier this year for $299 and I couldn't pass it up. I have one built and on my desk (it's a large desk) and I think it looks amazing. I appreciate and understand the critiques on the model. I'm just a guy who loves Star Wars and loves building LEGO. I also love coming to this forum and seeing all the amazing work people do. That said, I don't make my own MOCs and every LEGO Star Wars UCS I own, despite flaws that people point out, I think is fantastic. I love my UCS B-Wing, I love my UCS Jedi Star Fighter and I love my UCS TIE Interceptor! They were a blast to build, visitors and friends are constantly blown away by UCS collection since they aren't in the LEGO hobby. If you think you're anything like me I think you'll really enjoy having this model on display for many years to come, it is quite the conversation piece. Unless you are friends with any of the die hard LEGO fans on this site, all your friends and family that see it are going to be blown away and won't ever think to mention the flat bottom :)
Also, I don't collect mini figures, they can be sold off for a good amount of money on eBay, I made about $80 just selling the mini figures :) All of my UCS Imperial Shuttle and SSD mini figs were sold via eBay to support my future UCS purchases :) They paid for my B-Wing when it went on sale for $100 here in the states :)
Regarding an "investment" it will be interesting to see how this set appreciates after it's retired. Most people on the forums seem to think it won't go up that much. If you hold on to it long enough though, surely you can sell it for a little profit - I don't see LEGO ever doing this set again :)
Lastly - if you keep it long term and ever want to take on a new project, you can MOD it like many have done here :)