I am trying to use Zoho for all my business needs but now I find out that the UI between Zoho books and Zoho CRM is totally different.

Zoho CRM has the menus along the top, Zoho Books has it down the side. If I issue a quote in Zoho CRM and convert it to an invoice everything looks totally different to issuing an invoice in Zoho Books even though all the information is the same. I also find that the sync between the two isn't automatic.

Even the icon used for "setup" is a totally different image. The major reason for trying to stick to Zoho for everything is:

1) Everything should be integrated and should work flawlessly together 

2) I don't have to relearn a new UI with every module I buy

Is this true for every Zoho product? As I write this I am using Zoho helpdesk, and I note that here they don't even have a "setup" button its a button with my name on it and then I have to click setup later. So this is a 3rd way to do it. They've also done their menus differently (along the top but right justified rather than left)

As I use more Zoho products am I going to find that every product implemented everything differently and that there is absolutely no consistency? What the hell? 

Why should I even buy more Zoho products, why don't I just get something like Sugar CRM or Pipedrive and then try to integrate it with my other systems - as all this stuff seems totally different what should I bother with buying more Zoho products?