I've heard good things about them, and their after-sales service, although I've never used them myself. There are a couple of people who have complained about them also but when you dig into those complaints a bit they seem to be from some dead-heads who expect everything to be done for them for years after the sale and who don't read contracts before they sign them anyway.
Don't worry about "registers" - there is no professional register for "estate agents", since they don't exist in Bulgaria, and searches of local
cadastres (land registries) are best done when you've found a place and are in the process of checking it out immediately prior to buying. There's a very limited amount you can learn from searching the company register for the "estate agent" company since you presumably aren't buying the property from them and you'd be foolish, in my view, to save the money for a lawyer by getting the "agent" to handle the paper-work
As with anyone trying to sell you a property: research the area and the market carefully; check what other agents are selling in the area to get an idea of "average" prices - but always remember they're
asking prices and may well be over the top; "Google is your friend" - are they mentioned, for good or bad, on the net anywhere?
Never forget to get a good lawyer and read any paper-work VERY carefully before you sign it. Buying here can be perfectly painless - unless you shoot yourself in the foot!
And
DON'T give a POA to the "agent" - he/she is looking to make money out of you from the sale.....why on earth would you want to want to help them to do that or even imagine that your interests will be protected by them in any way? That's not to say they're all crooks but why give them the opportunity? Your lawyer is a much better bet - but try to ensure they really ARE lawyers and that they are recommended by people who have used them.