So, reporting back after a few months - the app is a little more polished, but they haven’t made any huge changes, just small improvements.
One big worry I had early on was that I’d have to report trades for CGT purposes as I’m not using their ISA, but it seems just deposits and withdrawals will count 
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The trading platform thus far is delivering fairly steady performance roughly in line with their promises. My small test deposit of 1k is up by 6.6% and steadily growing over a period where the S&P has gone from 3000 to 3000 with lots of volatility. Due to swings on Brexit news my freetrade portfolio is currently up more, but only since last week. I think I’d rather compare over a few years though, and wouldn’t deposit significant money with them before that. Overall I’m pretty happy so far.