Probably due to the cheaper rate, the service they...

Probably due to the cheaper rate, the service they provide compare to other law firms might be poorer, especially their email response time. Weeks gone by and no reply at all. Their staff might be over worked or probably just heck care. If timeline is cutting very close, it will get to your nerves.
For HDB matters, you can probably use them for very straight forward transaction since there are so many good reviews before me. Anything slightly different than the usual sales process like additional terms or conditions, you are better off paying someone more and get the response you need. Especially for unusual cases, they are not able to provide solutions for you. You have to crack you brain and make things work. Bascially, you are paying for them to do standard legal admin work.

Not really my kind of law firm. Engaged other law firms before, pricer but at least you get the answers and solutions you need.

On the plus side, Johnathan is a funny guy. You will have a good time chatting with him.