I checked back to this site and found it very much alive and kicking!
It's a catalogue and sales site, in fact I placed an order today as I found several parts listed which I want.
Much of the site is in French, including the checkout and payment pages. Perhaps English language versions will be added in due course.
Some pros and cons;
PROs
1. The site aspires to list every PM set and every PM part and has made a good start to achieving that aim, including pictures.
2. It's easy to see which parts are available to buy and to put these into your shopping cart. Prices seem reasonable on the whole.
3. You can 'flag' parts you want, effectively adding them to a wishlist (though I couldn't find how to view my wishlist edit found it, but it's another example of a drawback - see 'con' list point 1 end of edit). Sellers can see the wish lists and then list parts for sale, if they have them.
4. Searching with the advanced search option is quite effective, especially if you enter the part number.
5. When searching for a set, a list of component parts comes up, with colours, quantities and pictures, as well as availability of parts to buy.
6. The intention seems to be to encourage user contributions in future, generally a good thing I feel.
CONs
1. It's not a very well-designed website, with obscure menus, tiny clickable icons and uninspiring page layouts, but that may be improved in time and I am very familiar with PlaymoDB, which is much better presented, but that's just IMO!
2. Parts without Geobra Part Numbers have made-up numbers, a combination of letters and numbers. I don't know if these correlate with PlaymoDB's pnnnn or knnnn numbers, I haven't checked, but there are some cumbersome numbers reminiscent of Bricklink's cumbersome numbering of some Lego parts (or is that Lego's numbering system?). Likewise set numbers of older sets are numbered nnnnx as in PlaymoDB. Again, I don't know if these agree with PlaymoDB. In fact, I wonder how much of Mundobil's data comes from PlaymoDB and whether Heather was consulted....
3. If you don't know French, you might need to use Google Translate or Babel Fish on some pages, including most of the FAQs, but that will be addressed in time if people like me offer to help rather than criticising!
4. PF is omitted from the page of links to PM forums!