Hello Hillel,
Thanks for all the hard work.
I’m glad to see a full Dark mode in the UI. I’m not sure what stage of the UI design you are at, chances are you are well aware of the below but I’ll give my two cents anyway.
The interface is almost perfect for Mobile/Tablet use. However it is not great for the Desktop, where it is mostly used (at least in our case).
TLDR: I think simplifying the Desktop UI is a mistake. I believe the V1’s UI is great and V2 should try to closely follow it with some minor functionality enhancement. i.e. ability to add or remove rows in client, invoice, quotation etc lists.
Maybe ability to have a customizable dash for each section. i.e. if I go into invoices I’d like to see what is the total Inoviced for the period, how much of it was paid, how much is overdue, what’s the total tax to be paid for the period etc. A more flexible report framework would also be appreciated like the ability to create a completely custom report with fields from other tables etc. For example I’d love to create a report of paid invoices for the selected period and see when they were paid, is it full or partial payment, what was the net and what was the tax paid (taking into account partial payments) what is the payment reference etc.
The V2’s current major design issues on desktop are:
Horizontal design is way too cluttered. If Main Menu, Sub-menu, Selected Item Content and History are all open at the same time, that’s 4 sections on the main screen, that’s not counting tabs in the Selected Item Content section like details, items, etc.
The lists (clients, invoices, quotations etc.) should be more akin to v1, like a table (preferably with an option to add/remove rows). Most users would want to be able to sort Client list by balance, or alphabetically or see the clients primary email of phone number immediately without having to click through several more times.
There is no need for the “Selected Item Content” section, as per above I’d much rather a list of clients with a bunch of details take up the entire screen, If I want to drill down I’ll double click on the client.
Line items should not be in a separate tab on invoices or quotations or anywhere else similar to those. They should not have to be added 1 by 1. Anyone who composes long quotes/invoices daily will be pulling their hair out if they have to click for each line item. Once again V1 style is perfect - Editable table with a lookup field which fills the rest automatically if match is found, otherwise the rest of the info is entered by hand,seamlessly, without having to click (create new product etc) and product is created once invoice is saved.
While tabs are appropriate in certain places like Client details etc. I believe they are a hindrance for Invoices and Quotations, most people want to see all the information in front of them and scroll down. If you are trying to minimise the amount of initial info displayed better off using vertical expandable sections. Invoice preview however can go into a new tab… or a floating pop-up.
Hope the above is not too critical, it only relates to the desktop UI, the current V2 UI seems good for tablet and mobile. Although please fix the “go back” issue 
if possible. For example clicking on a client then clients invoices then clicking back takes you to main dash instead of the selected client.