There’s a little bit of a learning curve associated with using the TWS. The Mosaic version might be more accessible to beginners than the Classic TWS.
I can do most trades via the web interface easily (i.e. buying/selling long positions) and have recently successfully used it to shuffle several $100k from BND and BNDX into BINC and MTBA — a little less duration, a little more yield (and a little more TER …).
Trading options is easier via the TWS as you have (easier) access to option trading parameters and can customize the option chain; plus viewing and adjusting the order status is easier/more accessible.
In fact, I just initiated an option tradeLMT380PDec25 in the web interface earlier this afternoon and pretty much immediately changed to the TWS to proceed in order to watch the order and if necessary adjust it as clicking in the web interface to see the corresponding information was just too cumbersome.
Also, I wouldn’t know how to buy Treasuries in the web interface (for my Treasury Secured Puts (TSPs)). It’s probably (or almost certainly) possible in the web interface, but I know that I just need to launch the Global Bond Scanner in the TWS while I’d have to search for how to do this in the web interface.
Anyway, good luck and … enjoy? 
[LMT380PDec25] Sold a $380 LMT Dec’25 Put for $800 bucks. If it expires worthless, I will garner an above 5% annualized return on risk / capital allocated to the LMT option. If I am assigned, I am happy to have bought LMT for $380 near year end with expected fair value of 15xP/E of Dec 31 currently at $408.94
